How to check the computer's power supply for operability

The computer does not turn on? In this article you will find the answer to the question: how to check the computer's power supply.

A thesis solution to this problem is in one of our past articles.

After reviewing and applying our recommendations in practice, you came to the conclusion that, perhaps, the problem lies in the PC power supply.

Read how to check its performance in our today's article.

A power supply unit (PSU) is a secondary power source (a socket is the primary source), the purpose of which is to convert an alternating voltage to a constant voltage, as well as to provide power to computer nodes at a given level.

Thus, the PSU acts as an intermediate link between the electric network and the internal components of the computer and, accordingly, the operability of the remaining components depends on its serviceability and proper operation.

Causes and symptoms of a power supply failure

As a rule, the reasons due to which the power supply units fail can be:

low quality of the network voltage (frequent voltage drops in the network, as well as its going beyond the operating range of the power supply),

low quality of components and manufacturing in general (this item is relevant for cheap power supplies),

It is possible to determine a failed PSU or some other component by the following signs:

after pressing the power button of the system unit, nothing happens - there is no light and sound indication, cooling fans do not rotate,

the computer turns on after

the operating system does not boot or boots, but after a few seconds the computer turns off, although there is a sound and light indication and the fans are working,

BP verification can be performed in several ways.

We will talk about the sequence of each of the checks below, and now we will only confine ourselves to short information to understand what we will do.

The essence of the first method is to check the voltage supply and at this stage we carry out a rough check whether there is voltage or not.

The second way is to check the output voltage, we already mentioned that the voltage must be strictly within certain limits and deviation in any direction is unacceptable.

The third method is a visual inspection of the PSU for the presence of swollen capacitors.

For convenience, the algorithm of each of the checks will be presented in the form of step-by-step instructions.

What feeds the unit and what outputs does it have?

The power supply supplies the following PC components:

  • motherboard,
  • CPU,
  • solid state drives and hard drives,
  • drives
  • video cards.

Usually the power supply has several different outputs, for each of which it has a separate wire:

  • four- or eight-pin output for supplying current to the processor,
  • twenty or twenty-four-pin output for powering the motherboard,
  • Sata output
  • six- or eight-pin output for powering the video card,
  • molecules for powering various devices, for example, an additional cooler.

This is what these connectors look like.

If the power supply is defective, this can be determined by the following external signs:

  • PC does not turn on,
  • the computer freezes or shuts down,
  • The PC reboots by itself,
  • the power supply is very hot.

On a note! It should be noted that signs such as overheating or spontaneous shutdown do not necessarily indicate a breakdown. Sometimes overheating occurs when a relatively high load is applied to a relatively weak unit. For example, if you connect to a 350 W unit. Components with high energy consumption, he will not cope with them, which will lead to severe overheating, and then to trip protection and shutdown.

Symptoms of Malfunction

The internal device of the computer system unit

There are a number of signs that are characteristic of a malfunctioning battery. The power supply does not work in the desired mode under the following conditions:

  • Pressing the power button does not start the system unit. There is no light and sound response to the inclusion. Coolers do not rotate. In this situation, the power supply may malfunction or there may be gaps in the wires, weak supply of alternating current from the network,
  • The computer does not turn on the first time. The problem is either in the power supply, or in the loose connection of the connectors, or in the malfunction of the power button,
  • The computer shuts down for no apparent reason during the boot phase of the operating system. The reason for this may be intermittent transmission of voltage from the power supply to other computer components. This malfunction can also indicate overheating of the power supply and, as a result, it is forced to turn off.
  • The presence of a "blue" screen.
  • Presence of burning odor.

Key PSU Features

The presence of a reliable and high-quality unit in the computer is as important as possible for each component of the system. In this case, uninterrupted and error-free operation of the computer will be ensured. What is a power supply and why is checking the power supply of a computer so important?

A computer power supply unit (PSU) is a secondary source that equips a computer with electricity. Its main purpose is that the power supply passes to the computer nodes in the form of direct current, and the mains voltage is converted to the necessary indicators.

The functional feature of the power supply is based on stabilization and protection against small violations of the main voltage. BP also takes part in cooling the elements of the machine system. Therefore, it is so important to diagnose this component, which is almost the most important part of a computer of any kind. Since a malfunction in the operation of the PSU negatively affects the entire device.

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There are special standards that a PSU installed on a computer must comply with. First of all, it should work normally at a voltage for 220 v - 180-264 v, the frequency is 47-63 hertz. The unit must make sudden disconnections from the current source. When choosing a PSU, you should also pay attention to the connectors, which are divided into the following:

  • supply of leading HDD and SSD devices,
  • motherboard supply,
  • GPU graphics adapter
  • CPU processor supply.

Definition of sockets from the power supply unit

BPs have a coefficient of performance (COP) - the amount of energy that a computer feeds. High efficiency has several advantages. Among them are minimal electricity consumption, a little noise, since it works at lower speeds, a longer service life, because the temperatures are low, there is no overheating, less heating due to the reduction of heat that needs to be dissipated, etc. As a result, the remaining elements of the system receive “ high-quality feed ”, which means that the whole computer works smoothly and for a long time.

The power calculator will help you finally decide on the PSU model, which helps to calculate the power of the PSU. You can calculate it yourself. To do this, you need to know the approximate indicators of current consumption by various elements of a personal computer (PC). We already wrote in detail about How to calculate the power of the power supply for a computer.

The table shows approximate consumption options.

PC Hardware Name

Approximate indicator of electricity consumption, W

Memory module


CPU depending on TDP level in specifications








HDD and optical drive


Graphics adapter

Specifications in specifications

If the calculations correspond to 250 watts, then it is better to take with a reserve - 400-500 watts.

Causes and effects of nutritional problems

A complete failure and malfunction of the power supply most often occur due to:

  • Power surges.
  • Low quality PSU itself.
  • Inconsistencies of the PSU capabilities with the load consumption (computer devices).

The consequences of a malfunction of the power supply, especially in combination with a poor workmanship, can be not only damage to the PC electronics, but also a shock to the user.

Power supply voltage check

Step 1. Turn off computer. It must be remembered that the computer PSU operates with a voltage dangerous to humans - 220V.

Therefore, we strongly recommend that you turn off the computer before you follow all the other points in the instruction.

Step 2 Open the side cover of the system unit.

Remember, or for convenience, take a picture of how the power was connected to each component (motherboard, hard drives, optical drive, etc.) and then they should be disconnected from the power supply.

Step 3 Find a paper clip. With a clip, we will close the contacts on the PSU and if it was not at hand it would be suitable for a wire similar to a clip in length and diameter.

After that, the paper clip must be bent in the form of the Latin letter "U".

Step 4 Find a 20/24 pin power connector. This connector is very easy to find - it is a bundle of 20 or 24 wires, respectively, which come from the power supply and are connected to the PC motherboard.

Step 5 Find the green and black wire connectors on the connector. Insert a paper clip into the connectors to which these wires are connected.

The paper clip must be securely locked and have contact with the appropriate connectors.

Step 6 Turn on the power supply. We supply power to the PSU (do not forget to turn on the power button on the PSU itself, if it was turned off in Step 1).

Step 7 Checking the operation of the PSU fan. If the device is working and conducts current, then the fan located in the PSU case must rotate when voltage is applied.

If the fan does not rotate, check the paper clip for the green and black 20/24 connectors on the connector.

As mentioned above, this check does not guarantee that the device is operational. This check allows you to determine that the power supply is turning on.

For a more accurate diagnosis, you need to conduct the following test.

Checking at hand

You can check whether the power supply is working or not, by improvised means without any special equipment. It will not work to see if the voltage at the device contacts is normal, the check will only show if the power supply is starting up or not.

The verification mechanism is reduced to the following. The computer turns on when the user presses a button on the front panel. This button sends an electrical pulse to the motherboard, and that, in turn, closes two contacts on the twenty-four-pin connector of the power supply, after which it starts and after it starts the entire PC. Thus, in order to start the unit, it is necessary to close these contacts. Finding them is very simple: one of them has a green wire, and the other is black.

Any metal object that fits into the narrow groove of the plug is suitable for locking. Most often they are closed with a simple paper clip.

To check you need:

  • turn off the power of the computer,
  • open the system unit cover and remove the power supply from the PC. To do this, disconnect its connectors from the components, unscrew the screws holding it, and then carefully remove it,

The unit should turn on. If this does not happen, it is faulty.

You can also disassemble the unit and visually inspect it. Pay attention first of all:

  • on coils of copper wire, jumpers. They must be whole
  • on capacitors. They should not be swollen.

This is how the device looks from the inside.

This is how swollen capacitors look, which can cause a malfunction.

It is important that the cooler is turned on when the power supply is turned on. If this does not happen, overheating of the block elements and their further failure can occur.

Important Notice

The OCCT program very heavily loads the PSU during the test. If you are not sure about the quality of your power supply, then perhaps you should refrain from this test. The owners of cheap Chinese power supplies of an unknown or little-known manufacturer should pay particular attention to this remark. The same applies to laptop owners. For you, perhaps the best option would be AIDA64.

Still have questions, suggestions or comments? Contact us and ask a question.

Block inspection

Where is the power supply located

Checking the correct operation of the computer power supply involves certain manipulations under voltage. Be extremely careful to avoid accidents. Before starting the test, inspect the integrity of each cable. Do not touch parts with wet, unprotected hands.

Visual inspection of the power supply.

This is the first and easiest way to check.

  • Remove 4 (or 6) screws, disconnect the unit from the computer case,
  • Unscrew the screws that are in the block body and disassemble it,
  • Carefully inspect the power supply chip. Pay close attention to capacitors.

Inflated Power Supply Electrolytic Capacitors

If there are swollen among them, then the protection of the power supply is defective. Urgent replacement of parts is required.

If no problems are found in the capacitors, we recommend that you remove dust from the power supply, lubricate the fan and assemble the device, and then try connecting the computer.

What you need to know before you start testing the computer's power supply?

Testing a computer's power supply involves performing live work. You need to be very careful to avoid an accident. Before checking the power supply of the computer, it is necessary to examine the integrity of the braid of each cable. In no case should you touch the parts with wet, bare hands. If there is not enough experience in conducting such operations, it is better to consult a specialist.

For diagnostic measures, it is important to remember that diodes for replacement must be rated at 300 volts and above. And also must carry a current of at least 1 ampere. Remember, after changing the diode bridge, you do not need to turn on the device from the network, because you need to check all the components at once.

Checking the power supply occurs in several ways. The first and simplest is to visually assess the external state of the PSU. If there are inflated electrolytic capacitors and varistors, then the PSU protection is impaired. Parts urgently need to be replaced with new ones.

Inflated power unit electrolytic capacitors

If such a visual test of the power supply did not give positive answers, then you can use one of the diagnostic options - a computer program, a multimeter, a voltmeter, a special tester of the computer's power supply (such devices sometimes show inaccurate indicators).

How are the problems with the computer power supply

Symptoms of a feeder malfunction are very diverse. Among them:

  • Not turning on the PC when you press the power button or turning it on after repeatedly pressing.
  • Squeak, pop, clicks, smoke, burning smell from the power supply.
  • Blown mains fuse on the distribution board when you turn on the computer.
  • Static electricity discharges from the case and connectors of the system unit.
  • Spontaneous shutdowns and restarts of the PC at any given time, but more often under high loads.
  • Brakes and freezes tightly (before rebooting).
  • Memory Errors, BSoD (blue screens of death).
  • Loss of devices from the system (drives, keyboards, mice, other peripheral equipment).
  • Stop fans.
  • Overheating of devices due to inefficient operation or stopping fans.

Main parameters of PSU

The PC power supply produces several voltages necessary for the operation of all components of the computer.

The figure shows the largest 20-pin connector that connects to the motherboard. Indications are given for each contact.

Pinout and color scheme of the 24-pin connector and other PSU connectors

Multimeter check

If you have a multimeter at home, you can check the power supply with it. The fact is that each of the contacts of any connector in a working unit has its own voltage. Here is a schematic representation of these stresses.

The letters “GND” in the picture indicate “earth” (from the English “ground”).

For example, if we place one contact of the multimeter on the black wire (ground) of the twenty-four-pin connector, and the other on red (+5 V), then the readings of the device should be 5 V. Thus, you need to "probe" each of the wires of this connector and compare The result shown by the multimeter with the correct numbers in the figure. If all the data matches, then the power supply is working. If not, it needs repair.

In the case where the voltage at the contacts of the unit, there is nothing to worry about components. They will work worse, but are unlikely to fail. But if the voltage is increased, they can burn out, so the power supply having such a voltage must be immediately removed from the PC.

In addition, there are special devices for checking power supplies. They look like this.

In fact, they are nothing more than a voltmeter, but they have standard probe contacts, and connectors for connecting power connectors. When they are connected to the device, and the power supply is turned on, information on the voltage that the unit provides on each line will appear on the screen.

Here is a video on the procedure for checking the power supply with a multimeter.

Step-by-step procedure for diagnosing PSU with a multimeter

So, if the computer is unstable, it suddenly turns off, a blue screen appears, and there are problems when loading - it’s worth checking the power supply. This process takes place in several stages. First, you should examine the cooling. To do this, you can touch the top of the system unit, where the PSU is located. If obvious heat is felt, then the PSU overheats. The reason for this is a breakdown of the cooling fan in the power supply. After a little testing with a screwdriver, which is able to easily start the blades for several revolutions, if the fan is working, we decide on further actions. If everything is fine, we clean the fan from dust and start the computer. If the fan malfunctions, it should be replaced. We put things in order in this part - we will figure out how to check the power supply without a computer.

But for convenient work, you can still take it out.

Power check

This check is carried out by turning on the power supply without connecting to the motherboard.

  • Turn off the computer. Then turn off the switch on the back of the computer's power supply.
  • Remove the computer cover. Disconnect the power supply from other parts of the computer. Disconnect each cable. Be sure to remember or photograph the order of connection of all elements, then to connect all cables back.
  • Take the motherboard power cable that comes from the power supply. Find the green wire.

Motherboard cable

  • It must be closed with any of the black wires. Do this with a paper clip or a small piece of wire.

Short the green wire with any black

  • Connect a device to the power supply. For example, an old unnecessary hard drive. This is necessary to give the power supply a certain load, the absence of which can lead to damage to the unit.
  • Connect the power supply to the network and press the power button on the unit.

If the fan starts to rotate, then the power supply is working.

Even if this method of verification showed that the power supply is working, this does not mean that it is fully operational.

The principle of operation of the power supply

To understand if the power supply is working or not, you need to understand the basic principles of its operation. Simplistically, its function can be described as follows: the conversion of the input AC voltage of the household power supply to the output constant of several levels: 12 V, 5 V 5 V SB (standby voltage), 3.3 V and -12 V.

The following devices receive energy from a 12-volt source:

  • drives connected via SATA,
  • optical drive drives
  • cooling system fans
  • processors
  • video cards.

The wires of the 12 V line are yellow.

From 5 V and 3.3 V they are powered by:

  • sound, network controller and the bulk of the motherboard chips,
  • RAM,
  • expansion cards
  • peripherals connected to USB ports.

According to the ATX standard, the 5 V line is indicated by the red color of the wires, 5 V SB by purple, and 3.3 V by orange.

The 5 V SB (standby) source receives power from the computer startup circuit on the motherboard. The -12 V source is designed to power COM ports, which today can only be found on very old motherboards and specialized devices (for example, cash registers).

All of the ATX standard power supplies generate the above voltages, regardless of power. The differences are only in the level of currents on each line: the more powerful the feeder, the more current it gives to consumer devices.

Information about the currents and voltages of individual lines can be obtained from the PSU passport, which is glued on one side of the device in the form of a label. However, the nominal indicators almost always differ from the real ones. This does not say bad at all: fluctuations of values ​​within 5% are considered normal. Such minor deviations do not affect the operation of computer devices.

Among other things, a working PSU generates a Power Good or Power OK signal, which notifies the motherboard that it is working as it should and the board can start other devices. Normally, this signal has a level of 3-5.5 V and rises only when all the supply voltages have reached the specified values. If the power supply does not produce Power Good, the computer will not start. If it produces too early, which is also bad, the device can turn on and off immediately, freeze at boot or throw a critical error - the blue screen of death.

The Power Good signal is transmitted to the motherboard through a gray wire.

Using a multimeter to check power supply

Many users ask how to check the computer's power supply with a multimeter. It is very simple, knowing what tension and where it should come.

Before opening the PC case, make sure that it is not connected to a 220 V network.

  1. Open the PC case.
  2. Disconnect in turn the connectors from each device, having previously photographed or sketched the installation diagram.
  3. Pick up the connector that connects to the motherboard (usually the largest one) and make a jumper wire between 14 and 15 pins on the 20-pin connector and 16 and 17 on the 24-pin connector. Usually, green and black wires come up to them. A green control signal is emitted. The black wire is the earth.
  4. After that, connect the PC to the 220 V network.

If the power supply is turned on, then you can begin to measure the voltage at its contacts, according to the scheme presented above. If the computer’s power supply does not turn on, it means that it has failed, requires repair or a complete replacement.

When checking with a multimeter, between the black and red wires on the connector connected to the motherboard should be - 5 V, between black and yellow - 12 V, between the contacts black and pink - 3.3 V, between black and purple - the standby voltage is 5 IN.

If you do not have sufficient knowledge of electronics, it is better to entrust the repair of the device to specialists.

Voltage Check

  1. Turn off computer - we complete the work, wait for the device to be completely turned off, then on the back of the PSU you need to turn off the switch. Now exit the network.
  2. Open computer cover - Disconnect the PSU from other components of the device. The cables must be removed in turn, while it is important to fix the picture of the correct position of the cables using a photo or video.

  1. Doing the load - the computer turns off, but the check is under load. To do this, we connect the cooler with a special connector. Do not forget about the 220V cable.
  2. Take a wire substitute - a paper clip in the form of the letter U is inserted into the PSU after being turned off, you can also use a wire of a suitable diameter.
  3. Push the largest connector (20/24) - It is usually attached to the motherboard.
  4. Find contacts 15, 16 (green and black) - In order to touch a paper clip to these contacts.
  5. Insert a paper clip into pins 15.16 - then be sure to release it and you can connect the power supply to the network, turn on the switch.

  1. Check the operation of the fan - if the cooler is turned on, it means that the power supply is conducting, it is serviceable. If it doesn’t work, check the contact with the paper clip again and try again. If there is no result, the PSU does not work.

On this, the check of the computer power supply is not completed. It was a diagnosis of current conductivity. Next, you need to test the operation of the PSU. The computer power supply tester is based on the use of a multimeter.

Multimeter Test

Now you need to check whether the power supply transmits a constant voltage in full. For this:

  • Unplug the power supply and use a paper clip or a piece of wire to close the motherboard cable. So you bring the unit into working condition.
  • Give the power supply any external load. Connect a drive, hard drive or cooler to it,
  • Take a multimeter - this is a universal tester that measures the strength of current. Set the tester to DC voltage test mode.
  • Check the voltage between the orange and black wire, between the red and black, and also between the yellow and black.
  • We stick the black probe of the multimeter into the connector opposite the black wire, we connect the red probe of the tester in turn to the contacts of the connector, to which the wires of the colors we need fit.

Insert the tester probes into the pin connectors

A working power supply will produce the following voltage values:

  • 3 volts for orange wire,
  • 5 volts for red wire,
  • 12 volts for yellow wire.

If the test gave you a malfunction of the power supply, then it can be disassembled and repaired. After completing the work, collect all the contacts and make their correct installation.

If the test showed that your power supply is working, but difficulties with the computer continue, then most likely the reason is something else.

ATX Power Supply Main Connector Contacts

With the color marking of the wires 12 V, 5 V, 5 V SB, 3.3 V and 3-5.5 V Power Good, we figured it out. The remaining contacts have the following voltages:

  • White: -5 V. Left for compatibility with older devices.
  • Blue: -12 V.
  • The black: 0 V. Common wire or ground.
  • Green: 3-5 V. Power On. Closing this contact to ground is equivalent to pressing the power button on the computer. Starts the power supply. At the time of pressing, the voltage at the contacts of the button should drop to 0 V.

The same voltages are present on other connectors, which end the cables of the power supply, that is, in the projection of the yellow wire should always be 12 V, in the projection of red - 5 V, in the projection of orange - 3.3 V, etc.

Paperclip method

Among users, there is a simple method on how to check a power clip with a paper clip. Our resource will not be left aside, and will tell you what this method consists of, especially since almost the same thing was discussed in the section on using the multimeter. This is the simplest, one can say, home method, which cannot show the quality of the voltage source, but it will reliably make it clear whether it turns on or not.

  1. Disconnect the PC from the network.
  2. Open the case and disconnect the connector from the motherboard.
  3. Make a U-shaped jumper from a paper clip, which you need to short-circuit the green wire of the connector and the nearby black.
  4. Connect the power supply to 220 V.

If the fan has worked, then the PSU is theoretically in working condition, if not, it is definitely for repair.

Verification using special programs

You can check the power supply with the help of special test programs. One of them is OSTS Perestroika. You can download it for free on the official website of developers at:

To verify you need:

  • run the utility
  • click on the gear image

Important! Remember that they will check the power supply with the help of the Perestroika OSST for a malfunction, it is better not to. This software heavily loads the computer hardware, and it, in turn, heavily loads the power supply. Therefore, if you believe that the block is on the verge of "death", it is better not to put it at risk. The program is not intended to detect breakdowns, but to test the performance and stability of the system.

In addition, you can test the power supply with other programs, such as AIDA64. This program also gives a very strong load on all components of the computer during the test, so you need to approach the testing responsibly and conduct it with caution.

Program check

You can test the operation of the power supply using the specialized SpeedFan program.

This utility checks the temperature and voltage of the power supply.

When indicating the temperature of the power supply, this program operates with an internal thermal diode.

This allows you to more accurately determine the temperature.

  • Universal program for the test. If the power supply does not overheat, then there is no problem. It is noteworthy that the program during heating loads not only the processor, but also the video card. You can set your own voltage and temperature monitoring of the power supply - S&M. This utility heavily loads the processor, causing maximum heating devices.

Testing with this utility can cause the device to overheat and break if the components are of poor quality.

Unit Testing

  1. We put the multimeter into continuous current mode (voltage up to 20W).

  1. Disconnect the power supply from the network.
  2. By means of an improvised device - paper clips we bring the PSU into working condition, we connect the load through an optical drive. If the cooler does not spin, the PSU is faulty.
  3. We measure the voltage with a multimeter - we stick a black probe into the molex connector, which is located opposite the black wire (middle connector). We insert the red probe one by one into the contacts on a wide loop and follow the readings on the multimeter.
Measurement of voltage in the power supply through a multimeter
  1. In accordance with the pinout diagram of the PSU contacts, we determine the necessary voltage indicators for the PSU working condition. If the indicators do not match, this is a sign of a malfunction of the unit.

For convenience of verification, we present a pinout diagram of the PSU contacts.

+ 3.3V

+ 3.3V

+ 3.3V




+ 5V

Power on



+ 5V




Power good


+ 5V Standby

+ 5V

+ 12V

+ 5V

+ 12V

+ 5V

+ 3.3V


As an example, the red wires have a voltage of - 5V, if your indicator is 4V - this is a clear sign that the power supply check showed a negative result and your PSU is faulty.

If a breakdown is detected in the PSU, you can disassemble it and try to repair it. To do this, you need to have an elementary supply of knowledge on the operation of electrical devices. So, remove the cover, remove the dust and proceed to visual testing. What to look for? We are looking for elements on which there is blackening, swelling of capacitors, we are looking for dangling wires. It is necessary to inspect the inductor (inductor). A fuse or resistance may also blow.

Visual inspection of the computer power supply when not working

Didn’t find anything? Turn the board over, look at the adhesive paths and joints. We are looking for sealed elements that could simply have departed due to overheating or factory defects. The tracks that conduct current could burn out. In this situation, we simply replace the defective components, and the device will be in working condition. If the problem persists, consult a specialist. But do not forget, if the PSU is under warranty, then you should take it to a service center without opening the box.

Upon completion of the test, it is important to collect all the contacts and connect using the previously taken photo. Remember, if your PSU is working, and problems with the computer continue, the reason for this operation of the device may be hidden in other components. Test the system further until you find the cause and eliminate it.

How to check the power supply with a multimeter

The correspondence of all the voltages that the feeder generates to the given levels and the preservation of their values ​​at any loads (if they do not exceed the power supply capabilities) indicate that the device is operational and, most likely, operational. And to determine them, you will need a multimeter - an inexpensive compact device that can be purchased at almost any electrical goods store.

Multimeters (testers), of course, are different. Among them there are expensive high-precision models with lots of additional functions, but for our tasks simple enough. To test the power supply unit measurements to thousandths of a volt we do not need anything, there are enough tenths and sometimes hundredths.

Checking the performance of the power supply

As we said above, the computer PSU, regardless of other components of the assembly, is an important detail. As a result of this, failure of this part may lead to the complete failure of the entire system unit, which makes diagnosis much more difficult.

If your PC does not turn on, it is probably not the PSU that is to blame at all - remember this!

The whole complexity of diagnosing such components is that the lack of power in the PC can be caused not only by the power supply, but also by other components. This is especially true of the central processor, the breakdown of which is manifested in a huge variety of consequences.

We recommend that you take care in advance to find out the model of the installed device.

Be that as it may, diagnosing problems in the operation of the power supply device is an order of magnitude easier than with malfunctions of other elements. This conclusion is due to the fact that the component under consideration is the only possible source of energy in the computer.

The main symptoms and malfunctions

Faulty PSU, most often it just does not work, at all. But sometimes, the user is faced with problems that, by all indications, are manifestations of violations in the RAM or motherboard. In fact, the power comes from the PSU to the microcircuit, so failures in their work can indicate its malfunction. How to check the power supply in this case, and is there any point in repairing it, only a specialist can say. Next, problems will be described in which the cause may be BP.

  • Hangs when you turn on the PC.
  • A sudden reboot of the system.
  • Memory errors.
  • HDD stop.
  • Stop fans.

There are also characteristic malfunctions that the PC itself “talks about”:

  • Not a single device is working. The malfunction can be fatal, requiring the purchase of a new device, or simple, requiring the replacement of a fuse.
  • There was a smell of smoke. Blown transformer, chokes, inflated capacitors.
  • Peeps the computer power supply. Cleaning and lubrication of the fan may be required. A squeak when turned on also gives a crack in the core of the transformer, and swell capacitors.

In all cases, it is best to contact a service company in your city, where specialists will make a more accurate diagnosis and say whether it makes sense to further repair the device.

Power Supply Repair

If you even have a little soldering, you can try to replace the swollen capacitors on its board yourself. You can also try to replace the idle fan yourself.

To replace the capacitors you need:

    Disconnect the power supply from the computer. To do this, unscrew the screws in the rear of the case, disconnect the connectors from the components and carefully remove the unit.

To replace the fan, you need:

    Disconnect the power supply from the computer case, as described in the previous instruction.

If you are not very good in electronics, it is better not to try to repair the unit yourself, but to send it to a service center.

What will help extend the operation of the power supply?

So that the diagnosis of the computer power supply does not become a frequent process, it is important to adhere to several rules for the safe operation of the PSU. First of all, see how reliably and firmly fixed the PSU is in the system unit. When installing components with greater power, the load on the PSU also increases. Therefore, make sure that the conductor and semiconductor components do not overheat. And it’s better to immediately install a PSU with a power reserve, even when buying a computer. A good owner will not only monitor the current supply of his car, but will also timely and regularly clean the insides of dust, which fills all the parts and makes their work difficult.

In order not to think about how to check the health of the computer's power supply, it is important to ensure the constancy of the incoming AC voltage and protect against sudden shutdown. To do this, just put the uninterruptible and this problem will go by the wayside.

In addition to the power supply itself, you need to monitor the fan that cools the power supply. Periodically, it is necessary to clean and change the grease.

So, the rules for choosing a device:

  • do not buy very cheap power supplies because the quality will be appropriate,
  • do not chase after Watami. For a computer with a more powerful gaming video card, you should choose indicators - up to 550 watts. The rest will be enough and 350-400W,
  • When purchasing a PSU, monitor the ratio of price and Vata. The more wat, the more expensive the model,
  • A quality block will weigh a lot more than a fake.

You must adhere to the rules and monitor the safe operation of your computer at all times. But this does not mean that your computer is insured against breakage. If you hear a pungent smell of singed wires - expect trouble. After all, the device itself, which may have been acquired from a defective batch, can lead to such an outcome. If there is no guarantee on the PSU, you should try to test yourself, there is no result, you need to contact specialists.

Well, in order for the test result to please you, try to diagnose any suspected malfunction of the unit. Then there will be more chances to fix it and continue to use your favorite computer.

So, there are several ways to check the operation of the computer power supply. Here we learned how to do this with our own hands, if there is elementary knowledge of electronics in stock. Follow the instructions and the diagnosis will be successful.

Checking the power supply with OCCT

This utility also provokes maximum load on system elements.

The program is not recommended for use on weak or inexpensive systems.

Inside the utility there are several tabs responsible for the video card, processor, power supply. You just have to choose the right one.

Measurement conditions

The voltage measurements at the outputs of the power supply should be carried out under conditions in which a failure occurs. If the problem manifests itself in the first seconds and minutes of the PC, the instrument must be read immediately after switching on. If during intensive work - to obtain reliable results, the computer should be loaded, for example, with a heavy game or a program intended for this (for example, the OCCT utility, Power Supply test).

In order to track the change in supply voltage during the operation of a PC, measurements are best done continuously for several minutes or tens of minutes. If for some reason this is difficult, you can take one-time measurements at certain time intervals.

The result of a single measurement with a floating fault is often not an indicator, since in the event of unstable operation of the feeder, the voltage values ​​(or one of them) can constantly change.

Method 1: Verify the power supply

If at any time during the operation of your PC you find it inoperative, you must immediately check the availability of electricity. Make sure the network is fully functional and meets the requirements of the power supply.

Sometimes, power surges can occur, but in this case, the consequences are limited to turning off the PC yourself.

It will not be superfluous to double-check the power cord connecting the power supply to the network for visible damage. The best test method is to try to connect the used power cable to another fully working PC.

In the case of using a laptop, the steps to eliminate the presence of problems with electricity are completely similar to those described above. The only difference here is that in the event of a malfunction with the laptop cable, replacing it will cost an order of magnitude more expensive than with a full-fledged PC.

It is important to carefully inspect and check the power source, whether it is an outlet or surge protector. All subsequent sections of the article will focus specifically on the power supply, so it is extremely important to solve all difficulties with electricity in advance.

Power Supply Tips

So that the user does not encounter problems such as a breakdown or incorrect operation of the computer power supply, you need to follow a few simple rules when buying this device:

    Always purchase a power supply with some power reserve. The most optimal option is 100-150 watts in reserve. For example, if your system consumes 300 watts in total, you should not buy a power supply with less than 400 watts,

These tips will help prevent the failure of the power supply. If you follow them when choosing this device, it will last a long time and will delight the user with stable operation.

PSU Operation Tips

It is necessary to follow certain rules for the safe use of a computer power supply so that its testing does not become a frequent process.

  • Make sure that the power supply is securely and firmly fixed.
  • When installing components of higher power, the load on the unit increases accordingly. It is imperative to make sure that the conductive and semiconductor components do not experience overheating.
  • Even at the stage of buying a computer, choose a power supply with a power reserve.
  • Ensure and always verify that the ac voltage is constant.
  • Consider protection against unplanned shutdowns. Just install an uninterruptible power supply.
  • Watch for proper operation of the fan, on which the cooling of the power supply depends.
  • Systematically clean and change grease in the power system.

The above, unfortunately, does not guarantee that your computer is insured against breakage.

Try to test for any suspected malfunction of the power supply. In this case, the chance to repair the problem is much higher.

We examined several ways of how to check the power supply for operability. This can be done independently, with an elementary knowledge of electronics.

Do not forget to bookmark our article so that the instruction How to check the power supply is always at hand.

Measurement Procedure

  • Turn on the computer and bring it to a condition where a problem occurs.
  • Switch the multimeter to the constant voltage measurement mode (the icon on the instrument panel is circled by a yellow frame). Set the upper limit of the scale to 20 V.
  • Connect the black probe to any metal pad on the motherboard where the voltage is 0 V (for example, near the mounting hole), or to the pin in the connector that the black wire fits into.
  • Install the red probe in the measuring zone (in the connector opposite the corresponding wire). The number that you see on the tester's display is the voltage indicator in Volts.

Method 2: Using the Jumper

This method is ideal for initial testing of the PSU for its performance. However, it is worthwhile to make a reservation in advance that if you have never previously interfered in the operation of electrical appliances and do not fully understand the principle of PC operation, the best way would be to contact technical specialists.

If you experience any complications, you can put your life and the condition of the PSU in serious danger!

The whole point of this section of the article is to use a manually made jumper for the subsequent closure of the contacts of the power supply. It is immediately important to note that the method is very popular among users and this, in turn, can greatly help in the event of any inconsistencies with the instructions.

Before proceeding directly to the description of the method, you will need to disassemble the computer in advance.

    Disconnect all power sources from the PC.

Using a standard set of engineering tools, open the PC case.

Ideally, you should remove the power supply, but you can do without it.

Disconnect all connected wires from the motherboard and other assembly components.

It is advisable to somehow capture the appearance of the connected elements so that in the future there are no unnecessary problems.

You can learn a little more about disabling the PSU from a special article.

Having figured out the introduction, you can proceed to the diagnosis by using a jumper. And right away, it should be noted that in fact this method was previously described by us, since it was created primarily for the possibility of starting the PSU without using a motherboard.

Having familiarized yourself with the PSU startup methodology given above, after supplying electricity, you should pay attention to the fan. If the main cooler of the device does not show signs of life, you can safely make a conclusion about inoperability.

A broken power supply is best replaced or repaired by a service center.

If after starting the cooler is working properly, and the PSU itself is making characteristic sounds, we can say with a high degree of probability that the device is in working condition. However, even under such circumstances, the verification guarantee is far from ideal and therefore we recommend a more in-depth analysis.

How to check the performance of the feeder if the computer does not turn on

One of the common reasons for the computer not responding to the press of a power button is just the inoperability of the power supply. To confirm or refute this version, a metal clip or tweezers are enough with which we will simulate a button click. Remember, a little earlier we found out that for this you need to close the green and black wires on the 24-pin PSU connector, which connects to the motherboard? Just before that, it must be disconnected from it.

Next, in order:

  • Connect to the power supply, disconnected from the motherboard and computer devices, a certain load - the energy consumer. For example, an unused optical drive or a light bulb. Keep in mind that if the power supply fails, the connected device may fail. Therefore, use what is not a pity.
  • Plug in the power supply.
  • Use a paperclip to connect 2 pins opposite the green and black wires. If the feeder gives signs of life - it starts the fan inside, turns on the connected load, which means it is operational. However, operability does not mean serviceability at all, that is, this diagnostic method allows you to only differentiate a working device from a completely non-working one.

Method 3: use a multimeter

As can be seen directly from the name of the method, the method consists in using a special engineering device "Multimeter". First of all, you will need to acquire a similar meter, as well as learn the basics of its use.

Typically, among experienced users, a multimeter is referred to as a tester.

Refer to the preceding method, following all test instructions. After that, making sure that it is operational and maintaining open access to the main cable of the power supply, you can proceed to active actions.

  1. First you need to find out exactly what kind of cable is used in your computer. There are two types of them:
    • 20 pins
    • 24 pins.
  2. You can make the calculation by reading the technical specifications of the power supply or by counting the number of contacts of the main connector manually.

Depending on the type of wire, the recommended actions vary somewhat.

Prepare a small but sufficiently reliable wire, which is then required to close certain contacts.

If you use a 20-pin PSU connector, you should close the 14 and 15 contacts with each other using a cable.

When the power supply is equipped with a 24-pin connector, you need to close the 16 and 17 pins, also using a previously prepared piece of wire.

After completing everything exactly according to the instructions, connect the power supply to the power supply.

  • At the same time, make sure that by the time the power supply is connected to the network, nothing intersects with the wire, or rather its bare ends.
  • Do not forget to use hand protection!

    As in the early method, after power is supplied, the PSU may not start, which directly indicates a malfunction. If the cooler still works, you can proceed to a more detailed diagnosis, using the tester.

      To simplify the understanding, we will take as a basis the color scheme of the contacts, in accordance with their role.

    Measure the voltage level between the orange and black wires. The indicator presented to you should not exceed the value of 3.3 V.

    Perform a voltage check between the violet and black terminals. The resulting voltage should be 5 V.

    Test the red and black wires. Here, as before, there should be a voltage of up to 5 V.

    You must also measure between the yellow and black cable. In this case, the final figure should be 12 V.

    All the values ​​given are rounding of these indicators, since minor differences can still be due to certain circumstances.

    After completing our requirements, make sure that the data obtained complies with the voltage level standard. If you have noticed quite significant differences, the power supply can be considered partially faulty.

    The voltage level supplied to the motherboard is independent of the PSU model.

    Since the PSU itself is a rather complex component of a personal computer, it’s best to contact a specialist to fix it. This is especially true for users who are new to the operation of electrical devices.

    In addition to the above, a multimeter may well be useful in the process of checking the laptop's network adapter. And although breakdowns of this type of PSU are rare, you can all be found to have problems, in particular when using a laptop in fairly harsh conditions.

      Disconnect the network plug from the laptop without disconnecting the adapter itself from the high-voltage network.

    Having previously switched the device to calculate the voltage level in volts, take a measurement.

    It is necessary to find out the degree of load between the middle and side contact, in accordance with the screenshot presented by us.

    The final test result should be around 9 V, with possible minor deviations.

    The laptop model does not affect the level of power supplied at all.

    In the absence of these indicators, you need to carefully examine the network cable again, as we said in the first method. In the absence of visible defects, only a complete adapter replacement can help.

    What methods for diagnosing computer power supplies still exist

    Checking the power supply with a multimeter and a paper clip is enough to identify its malfunction in about 70-80% of cases. If you do not plan to continue to repair it, then this may well be limited. In professional diagnostics of power supplies, not only these, but also other methods are used to localize the defect. Including:

    • Check the ripple of the output voltage using an oscilloscope. This is a rather expensive device, so hardly anyone decides to buy it for a one-time operation.
    • Dismantling, inspection, testing of voltages and resistances of printed circuit board elements for compliance with standards. It is dangerous to do this without special preparation, since power supplies accumulate in some parts the voltage of the household power supply. Accidental contact of any element under voltage can result in electric shock.
    • Current measurement It is carried out using an ammeter built into the tester, which is included in the gap of the tested line. To create a gap usually solder the elements of the board.
    • Testing on stands with specially selected equipment in various operating modes.

    In short, there are a lot of methods for diagnosing power supplies, but not all of them are applicable and advisable at home. Except for research purposes, unless, of course, this interests the owner.

    Method 4: Using the Power Supply Tester

    In this case, for analysis, you will need a special device designed for testing PSUs. Thanks to this device, you can connect the contacts of the PC components and get the results.

    The cost of such a tester, as a rule, is somewhat lower than that of a full-fledged multimeter.

    Please note that directly the device itself may differ significantly from that given by us. And although the power supply testers come in different models that differ in appearance, the principle of operation is always the same.

      Read the specification of the meter you are using to avoid difficulties.

    Connect the corresponding wire from the PSU to the 24-pin connector on the case.

    Depending on your personal preferences, connect the other contacts to the special connectors on the case.

    It is recommended to use the Molex connector without fail.

    It is also advisable to add voltage from the hard drive using the SATA II interface.

    You may need to hold the button briefly.

  • The main indicators are only three:
    • + 5V - from 4.75 to 5.25 V,
    • + 12V - from 11.4 to 12.6 V,
    • + 3.3V - from 3.14 to 3.47 V.
  • If your final measurements are lower or higher than normal, as mentioned earlier, the power supply requires immediate repair or replacement.

    Method 5: Using System Tools

    Including cases when the PSU is still in working condition and allows you to start the PC without any special difficulties, it is possible to diagnose malfunctions using system tools. At the same time, note that the check is mandatory only when obvious problems in the behavior of the computer, for example, spontaneous switching on or off, are noticeable.

    To run the diagnostics, you need special-purpose software. A detailed review of the most relevant programs was made by us in the corresponding article.

    Before proceeding to the manual itself, you should understand that the calculation of problems with the PSU occurs by taking readings from your device and the subsequent maximum load of the power source. Thus, actions taken can entail disastrous consequences.

      Run the program to test the components of the computer and carefully study the presented indicators.

    Go to a special site where you need to fill in all the fields presented in accordance with the data from the diagnostic tool.

    In block "Results" press the button "Calculate"to get recommendations.

    If the installed and recommended PSUs do not match each other in terms of voltage, it is best to abandon the idea of ​​further testing and get a suitable device.

    In the case when the power of the installed power supply is more than enough for maximum load, you can start testing.

      Download the OCCT program from the official website, thanks to which you can provoke maximum PC load.

    Having launched the downloaded and installed software, go to the tab "Power Supply".

    If possible, select the selection opposite the item “Use all logical cores”.

    Click on the button "ON"to start the diagnosis.

  • The verification process can last a very significant period of time, up to an hour.
  • If there are any difficulties, the diagnostics will be interrupted due to an automatic restart or shutdown of the PC.

  • More serious consequences are also possible, in the form of the failure of some elements or the blue screen of death (BSOD).
  • If you use a laptop computer, this kind of check should be performed with extreme caution. This is due to the fact that the working elements of the laptop assembly do not predispose to heavy loads.

    On this, the method can be considered complete, since upon successful completion of the test, all suspicions of BP malfunctions can be safely removed.

    At the end of the article, it should be noted that in general there is a fairly large amount of information on the diagnosis and repair of the power supply in the network. Thanks to this, as well as our help through comments, you can easily find out what state your PSU and the computer as a whole are in.

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