The computer does not turn on, what is the reason. Start or Power button does not work

Good day everyone. Today the topic of our computer conversation is devoted to the case when you turn on your computer, but it does not turn on. The moment, you see, is not a pleasant one. Moreover, yesterday you worked quietly, turned it off, and today nothing turns on.

There can be many reasons for this. Some of them can be eliminated on their own, others only with the help of a specialist. But before we run to the workshop, let's look at these reasons. Maybe you can fix something yourself.

What could be causing your computer to not turn on? First, let's determine how it doesn't turn on: it doesn't turn on at all, it turns on but doesn't load, or it turns on but the monitor is clean.

These cases can be divided into two problems: problems with hardware and problems with the system. If the coolers are working, the computer beeps, the monitor starts running the BIOS and that’s it, then the problem is in the system itself. It’s a little simpler here, we reinstall and move on. Otherwise, you have a hardware problem.

Here are the top most common reasons for this:

Power problem
Power supply burnt out
Monitor is faulty
The battery on the motherboard is dead
System unit contamination
Problems with connecting components or cables
Power button malfunction
Motherboard failure

If your computer does not turn on, the first thing you need to do is check whether voltage is supplied to the computer. Here, first of all, we check the power supply itself. It has an on/off button. Maybe it was turned off.

In addition, the power supply can be checked by replacing it with a working one. We disconnect all the cables from the motherboard and in their place we connect another power supply, a working one. If everything works with it, then the problem is in your power supply. If you do not have another power supply, then using any conductive material: a paper clip, etc. You will need to close the green and black contacts on the unit being tested. If the fan starts working, then the unit is ok.

Checking network cables

Next, check the network cables. Perhaps one of them is poorly inserted, or it simply needs to be replaced. If your computer operates via a UPS, then you need to check that too. If the computer is connected through a surge protector, then the problem may be there. We also check its performance.

Checking the power buttons

We check the power buttons on the processor. Sometimes they get stuck. If everything is fine, then we look for the power connectors on the motherboard (the instructions for it have all the descriptions with pictures). We take out the plug and close the contacts with tweezers.

The computer will either turn on, then the problem is the button, or not.

Resetting BIOS settings

If your computer does not turn on, then try resetting the BIOS settings. This is done using a special jumper located next to the battery. Remove the battery for a couple of minutes. After this, the settings will be reset to factory settings. You can even replace the battery itself.

Also, do not forget to clean the board and all its components from dust. After that, turn on the computer again. If it doesn’t help, move on to checking all components

Checking computer components

First, we remove everything that is installed on it from the motherboard: processor, RAM modules, hard drive. We leave only the power supply, the motherboard itself, and the power/reset button wires connected to it. After that, turn on the computer. What should it be? If the power supply fan does not spin or it starts but turns off after a few seconds, then the motherboard is faulty. We replace it. If the fan rotates normally, then the problem is not with the motherboard.

The next steps are as follows: we insert each component one by one and turn on the computer. If the computer works after the inserted component, then this element is working. If it does not turn on, then it will be necessary to replace the faulty part. Memory modules must be tested through all slots for which they are intended. It may turn out that the problem is a malfunction of one of the slots.

The last thing we check is the hard drive. If the computer turns on but does not start, then see if the processor sees it. If it sees it, the problem is in the operating system; if not, it’s in the hard drive itself. It needs to be diagnosed. In addition, when you turn on the computer, listen carefully to see if the hard drive makes sounds and what kind of sounds they make. If it hums normally, then the disk is intact, but if it is silent or sounds differently, then most likely it is broken.

So, let's summarize what you need to do to check your computer:

find out that the power supply is turned on
check the serviceability of the outlet to which the PC is connected
Check if the PC power cable is working properly
clean your computer
check the health of the power supply
check the functionality of the PC power button
find out the presence or absence of swollen capacitors on the motherboard
Check the BIOS battery, replace if necessary
check the health of the hard drive (you can put your hand on it and if it vibrates, then everything is fine with it)
check memory modules through all slots for their connection

If none of the above helped, then you need to take the “sick” to a service workshop.

Hello dear readers!

We continue our topic of computer equipment repair. Our article today will be devoted to what to do if your computer (or rather the system unit) does not turn on. Or it happens like this - the system unit turns on, the fans are noisy (the coolers are working) as usual, but the monitor is quiet and dark... It’s just a black screen and the speaker doesn’t beep.

So, in our last article (), we looked at problems with the Windows 7 and Windows 10 operating systems in software terms, and also touched on the following possible problems, which relate more to technical issues related to peripherals and hardware. And which we didn’t have time to sort out in the last article.

Subscribe to the blog to not only know, but also understand computer issues. We try to help exclusively with your problem. But please note that symptoms and causes may vary. And if you have a special problem, then write below in the comments.

So, the common reasons that occur are as follows:

Well, today we will talk exclusively about problems with starting the computer. And along the way, I will also tell you how to solve a number of other problems.

The article turns out to be long, because there are actually many reasons, but the symptoms are the same, I have already listed them.

In general, today I will try to combine these reasons and problems into one solution. Because we have a reason for this - we will perform an autopsy...

We will open the system unit! This is a bold decision, so why don't we touch on the basics today - you will learn when it is necessary and when it is not so much. And learn to do it yourself.

« But can we open it ourselves - it’s dangerous!"- the cautious reader will exclaim.

I hasten to reassure our readers...

Of course, if the computer is still under warranty, you cannot open it!

But in other cases it is possible. I’ll tell you why now. At the dawn of the development of modern computers (this is approximately the beginning of the 80s of the 20th century), most companies produced their personal computers (to put it in one word) - “disposable”. The most famous representative that has still maintained this trend is the corporation Apple. When such a computer becomes outdated, it is quite difficult to update its hardware. It's easier to buy a new one. Here's the company IBM long ago proposed a different principle. The case contains removable filling - from different manufacturers. And the user can assemble his own computer like a construction set - as long as the parts are compatible. And if a “part” breaks, you can throw it away and replace it with a working one. Or more productive .

This principle is called " Open Architecture Principle" Thanks to him, “IBM PC compatible” system units quickly ousted Apple and other computers from the market. And because of this, you and I use Windows, not MacOS. And the “designer” trend is still relevant for us.

Except laptops! Laptops (and all-in-one PCs) are a separate class; their hardware depends entirely on the manufacturer and the specific model. This principle does not work for them.

Solution to the problem:

When the computer turned into a “patient”.

We are preparing him for the “operation”. First you need to disconnect everything from it - keyboard, mouse, monitor, power, webcam - turn everything off, put the “patient” on the operating table. To carry out the “operation” we first need: good lighting, a Phillips screwdriver, a small brush, wet alcohol wipes, and if there is a lot of dust, a vacuum cleaner..

We place the system unit with the top cover facing us, look for two metal bolts and unscrew them.

We pull from the side of the unscrewed bolts - we pull the cover until we pull it out, and this is approximately what we see:

So, the autopsy showed that death was caused by an autopsy...Hm.... What am I talking about?

We begin to solve problems in order.

Problem 1: The computer does not start. The system unit does not emit a short squeak when starting up. Black screen; the fan and the system unit are working... But the computer does not turn on the first time, only after a reboot (Hmm... and what are the reasons?)

And the reasons are usually:

- static electricity;

— CMOS or, in common parlance, BIOS has failed;

— equipment connected through slots to the motherboard does not work. These include video cards, network adapters, modems, RAM, recording, transmission, and storage devices, as well as USB connectors and card readers.

The power supply is faulty

Computer motherboard is faulty (severe but relatively rare case)

Despite such a frightening list, you can handle it on your own; it’s not as difficult as you might think.

Read carefully and do everything slowly - and you will succeed!

Warning. All actions must be performed with the power completely turned off. If these requirements are not met, the motherboard may fail; the author of the article is not responsible in this case!

Let's carefully inspect the connectors from which you just disconnected all the peripheral devices; carefully inspect the connectors on the front panel.

Very often the reason lies in them - the plug from the headphones was broken - it remained inside; The USB connector(s) were broken with a flash drive, the contacts are bent, sometimes there are foreign objects, dirt, dust inside. We inspect all connectors - keyboard, network card, monitor, card reader. There should be no damage, bent or closed contacts

This is what good connectors look like:

In case of damaged connectors, use a thin needle to straighten the contacts so that they do not touch; We seal the faulty connector with tape or tape and don’t use it anymore.

If everything is in order, we proceed to inspect the motherboard.

We continue our inspection...

The first thing we see is dust. There is no dust in my photo anymore, but you have it. Dust is a source of static electricity. Accumulating inside, it settles on conductive elements and accumulates an electrical charge. The power supplies “see” its presence, go into protection, and here’s another reason for you - the computer works, but does not start (does not start). Use a brush to brush off the dust. When there is a large accumulation of dust, we actively use a vacuum cleaner and remove dust from the fans. Carefully wipe off a thin layer of dust with an alcohol wipe wherever you can reach it.

We use the vacuum cleaner carefully, it is better to turn it on for blowing, and in any case keep it at a distance from the board. You just need to get rid of the dust. And often, it’s enough to just lower yourself and blow hard with your mouth so as not to damage anything! Also try not to use wet wipes or wipe the boards under any circumstances. Only wiping outside and inside the case is allowed.

You need to act carefully, and under no circumstances use fanaticism or force.

Use a thin screwdriver to remove the round battery from the socket.

We check its voltage.

If it is lower than what is written on the battery, replace the battery. By removing the battery, we completely deprive the board of power, and at the same time some BIOS settings will be reset to factory settings. Replacing the battery also solves some problems starting the system unit - and another possible problem has been eliminated.

By the way! Even without checking the battery for charge, you can simply replace it with the same one. Just take it and buy the same one at the nearest computer store in your city. A dead battery is one of the common reasons when a computer does not start. There's just not enough tension! The problem rarely occurs on computers less than 3 years old. Typically, the battery lasts for 3-5 years, in my experience. If you have encountered the same problem, please write a comment below.

We continue to solve the problem with starting the computer...

Disconnect all cables from the motherboard - hard drive(s), power supply:

This is how the power supply connectors are disconnected:

And here:

Hard drive(s); disconnect the power (the same connector on the DVD drive):

If a removable video card is installed, disconnect it too. We unscrew the screw, take out the card, and inspect it. We remove dust, and also wipe the video card slot from dust with a damp cloth. We inspect the video card fan - remove all the dust from under it; Let's check if it's loose. If everything is in order - good, if not - read on.

Warning: Do not touch the wires going to the buttons of the system unit and to external USB ports unless necessary; Removing them takes much less time than putting them back in place!

If there are more devices in adjacent slots, take them all out and repeat the steps.

We take out the RAM sticks:

Press the latches and pull the strips out of the slot. We carefully remove dust everywhere with a damp cloth.

We use the vacuum cleaner and napkins diligently- to all slots.

Having freed the motherboard from the equipment, we carefully remove any remaining dust from it.

Hooray! The system unit and motherboard are clean! If dust is to blame, we have fixed the problem. If not yet, we still did some general cleaning and preventive maintenance.

Problem 2: The fan is running full (the cooler is humming or making noise), but the computer does not turn on or freezes

Now is the time to consider a solution to this problem. While all the organs have been removed and the patient is “under anesthesia” on the operating table. It's time!

We are talking about a processor or CPU fan. Who remembers the movie "Terminator 2"? It was a cool story!

Hooray! Now we will also get to the processor))

Warning! On different types of motherboards, the CPU fan heatsink mounts are different! As an example, mounts for Intel processors. They are cunning, more cunning than AMD. It's easy to remove, but more difficult to install without damaging it. Be careful, careful and don't rush.

Why do we remove the radiator and fan? This must be done when replacing them, to clean the radiator from dust and to apply fresh thermal paste to the processor. All these measures designed to protect yourCPUfrom overheating.

We will also add the following symptoms of overheating:

Problem 3: The computer turns off by itself during the game (which is independent)

Other problems can also be included here. Namely:

Sudden shutdown of the computer after turning on and fully loading Windows;

The computer does not turn on, but the coolers work, the screen is black and the speaker does not beep (and this happens...);

The fan in the computer is humming. The cooler is so noisy in the system unit that it is impossible to work...

Warning! These symptoms may fully apply to a malfunction of the video card, including the one on which the fan is installed.

Sometimes, if settings are made when the processor overheats, the system unit emits prolonged squeaks (more often during hot weather) and turns off after a short time, or it beeps for a long time immediately after startup.

On older models there are noisy processor-cooler connections. Over time, noise arises from wear and tear on the fan bearings. In these cases, the radiator with fan must be replaced with a more modern and less noisy one. Before continuing the repair further, write down the name of your motherboard, it is almost always on the board itself (photo below) and in the store select a suitable cooler for it. It always comes complete with a radiator and the price is low. At the same time, buy thermal paste.

We turn in the direction of the arrow (which is pushed aside) all four latches one by one. We lift the clamps one by one, then lift the radiator too. Don't forget to disconnect the power supply to the fan.

Removing the remnants of old thermal paste from the processor and cooler

Carefully apply the new one, a small amount of paste is required. As shown in the image below. Next, just gently smear it with your finger (the main thing is not to overdo it...).

Carefully put the radiator in place.

Attention! Insert the latches into the board very carefully, without using force, until you hear a characteristic click. Only after making sure that they have become correctly - carefully press down, otherwise you will break them. Afterwards, do not forget to turn the latches into place.

If the radiator stands firmly and does not jump out or dangle, then that’s it! Life has been made easier for the processor.

Problem 4: The monitor does not turn on when the computer starts (does not show an image, but the light blinks and the computer works)

This is one of the symptoms of a video card failure. There is a video card - built-in (looks like this)

...and not built-in 🙂 (discrete), it...

...inserted into the motherboard slot.

In our example, there are two cards. If you also have two installed at the same time, it’s very easy to check which one is not working. Usually, if the “discrete” one stops working, we disconnect the monitor from it, be sure to pull it out of the slot, and connect the cord from the monitor to the built-in one. Otherwise, you need to do the opposite. As a rule, an image from one of the cards will definitely appear.

In some cases, video cards begin to fail when their fan is broken or “erased.” You can also try to change it by picking it up in the appropriate store. We replace the faulty video card. If you only have a built-in video card on your computer, you need to buy a new – discrete one; compatible ones are selected for the motherboard based on your preferences.

In general, if the problem already arises in replacing computer parts, but you have no experience, then the best thing to do is contact a service center, where they will advise you free of charge and also recommend improving and upgrading your computer or laptop.

Motherboard marking:

Problem 6: RAM

A malfunction of RAM modules or sticks can also prevent the computer from starting, causing failures and freezes. If we see that the PC starts without RAM sticks, but not with the RAM sticks, it means poor contact due to incorrect installation, or one of the sticks has failed. Again, we select a new bracket based on compatibility with your motherboard, size and price.

Installing more RAM significantly speeds up your computer!

Problem 7: Power Supply

The last malfunction that we will consider today concerns the power supply.

Power supply failure is a common occurrence. All the symptoms listed above can also apply to the power supply when it fails. He also has a fan that can make noise and fail. There are electronic components that fail over time.

If you have completed all the above steps, installed everything in place, and the computer still does not start, check the power supply. I do this by connecting a working unit to the motherboard (not necessary to other devices yet). I don't remove the old block yet. If the computer starts successfully, I replace it with a new unit, of the same power and with the same number of connectors (there are different numbers, this must be taken into account).

The power supply is very easy to change. After you have completely disconnected its connectors from all devices, unscrew several screws on the case:

...we install a new block, fix it with screws and that’s it.

Warning! If you plan to install more powerful equipment on the board - (for example, an additional video card or additional hard drives), the power of the new block should be higher than that on the old block. The higher the better!

After we've finished everything, we carefully put all the devices in place - first the processor cooler, the new power supply; then RAM, then video card; connect the power supply to the motherboard. We put all other devices in the slots. Connect the monitor.

Don't forget to put the coin cell battery back in place.

After everything has been checked, we connect the power. The computer should start with a short, triumphant squeak. There is no noise. A picture appeared on the monitor. Hooray!

Turn it off, replace the cover from the system unit, and secure it with screws.

So, wait, what kind of detail is this?Oh, this is from another TV!:):):):):)

We connect all the wires in their places. That's it, our “patient” came to life and recovered.

In this article, I have consistently tried to acquaint you with the process of self-diagnosis and troubleshooting - from beginning to end, but you can start, for example, right away with the power supply if you are sure that the problem is in it. This is a matter of a specific case. The principle “Don’t interfere with the machine’s work” must also be observed. 🙂

This article is for you, decide for yourself. In it, I did not touch on the repair of motherboards and hard drives. Because this is a separate big “sore” topic.

If you have specific questions, write in the comments, they will definitely help you.

That's all for today. To all readers - more health and good mood. Bye!

BIOS is the Basic Input/Output System, the heart of the computer, without which the normal operation of other components and software is impossible. When you turn on your computer, the BIOS starts first and only after you turn it on, the operating system starts loading.

Theoretically, since Windows boots after the BIOS, reinstalling the operating system or adding another OS should not affect the normal operation of the BIOS. However, there are often cases when an attempt to install a second operating system results in the BIOS not loading.

In this case, we can assume that the BIOS settings have gone wrong and restoring the default settings may solve the problem. To reset the settings, you need to perform the following operations.

Disconnect the PC and monitor from the electrical network.
Open the system unit and remove the battery from the motherboard.
Wait a few minutes.
Return the system battery to its place.
Connect power to the computer and monitor.

After restarting, the BIOS will start loading “like the first time”. If the problem goes away after this, it is recommended to format the boot hard drive and reinstall the operating system. Preferably one that has previously worked without problems. It is quite possible that the added operating system was damaged in the distribution.

Connection problems

There is a high probability that the BIOS does not load due to breaks in the power supply networks or data loops. To check this option, you first need to listen to see if the cooler on the motherboard is spinning. The BIOS is part of the processor and therefore poor cooling of the motherboard leads to malfunctions.

Perhaps the contact groups of the fan have come loose, which is why it does not work. After this, carefully inspect all cable and cable connections. Check to see if dust has accumulated on the motherboard or contacts. Dust is an excellent conductor of electric current, and it also creates electrostatic fields, to which electronics are very sensitive.

Clean the device from dust using a vacuum cleaner and a brush.
Sequentially disconnect the contactors and clean the terminals from dirt and oxidation. You can use a school eraser to clean the contacts.
Check that all connectors are securely attached. It is likely that vibration caused the contacts to separate, and therefore the equipment stopped working correctly.

After the maintenance, you can try to start the computer again. The screen is black again and the BIOS won't load? Then we can assume that one of the internal modules is faulty. Including the motherboard itself could fail or need to be reflashed.

You can download the new firmware for the motherboard on the manufacturer’s official website. Updating the firmware is a difficult and quite risky task. Therefore, if you don’t know exactly what and how to do, it’s better not to take risks, otherwise you could ruin your entire computer, including the hard drives. It is better to contact the service center.

Faulty blocks in the computer

None of the above helped? Then the likelihood of hardware failure increases and you can start checking the blocks.
Disconnect and remove anything from the device that is not necessary for the computer to start. Leave only the motherboard, power supply and one of the RAM sticks. The computer will not work in this state, but it is possible to check the serviceability of the motherboard itself.
A common reason for the inability to start a computer is insufficient power from the power supply. For example, you replaced the motherboard with a more advanced one, which requires more electricity. However, the power supply remains old. Or so - additional hard drives or some other functional components were installed in the system unit. Energy consumption can increase quite significantly. Installing a more powerful power supply will solve the problem. If the issue, of course, is a lack of energy.

Often, loading the BIOS is prevented by a malfunction in the video card. If possible, you need to check the video card by replacing it with another similar one. Or install the video card in another computer. Here you need to look at the compatibility of the equipment. Otherwise, you won’t find the problem, but you may create new problems.

If the minimum configuration - motherboard, power supply, RAM socket - the system unit is working and the BIOS is loading, then the problem is in one of the removed modules. After installing and connecting the next unit, try turning on the computer again and see what happens. As soon as the BIOS stops starting again, we can assume that you have discovered a faulty unit. Now all that remains is to find a similar one and replace it.

In reality, everything often turns out to be much more complicated. For example, the computer sometimes boots and works quite normally, and then, for no apparent reason, it starts to fail. The problem can be either software or component failures.

Such periods of normal operation, alternating with the inability to load the BIOS, are typical for three types of problems.

Presence of microcracks on the motherboard. Because of this, contact periodically disappears.
The electrolytic capacitors on the motherboard or power supply have dried out. This malfunction mainly applies to old system units that have been in use for a long time. Sometimes faulty capacitors can be identified by characteristic swelling of the housing.

Poor contact in the connected wires. As already mentioned - the presence of dust, oxidation of contacts, insufficient pressure. If the contactors have fixing screws, they must be tightened completely. The opposite situation also happens - clamping screws that are tightened too tightly lead to deformation of the connectors and poor contact in the connection.

In fact, if the computer does not turn on, you can determine the reason yourself, without having any skills. In this case, there are not many reasons, and you can determine what has gone wrong in literally 5 minutes. This is exactly what I want to talk about today, how to do independent computer diagnostics.

To avoid filling your head with unnecessary information, use the article navigation and go straight to the section with your symptoms.

The computer does not turn on and beeps

Let me guess, you probably opened the computer to clean it or change components? But, there are times when no one touched the computer, and it itself began to make squeaks when turned on. Be that as it may, the speaker gives a signal that something is connected incorrectly or is out of order.

Your PC can beep in different ways, it can be: short/long beeps, 3-5 beeps, or even continuously. Each of these signals indicates a specific problem, but each BIOS has its own signals. First you need to determine what version of BIOS you have. The easiest way is to remove the PC cover and look at it, look for a chip there with the inscription BIOS, and under it there will be its version (AWARD, Phoenix, AMI, Intel, UEFI).

Now that you know what BIOS you have, remember the number of signals, look at the table below and it will become clear what your problem is.

BIOS Award Signals

Signal type
1 continuous signal	Problems with the power supply.
1 repeating long	Problems with RAM.
1 long + 1 short	RAM fault.
1 long + 2 short	Video card error.
1 long + 3 short	Problems with the keyboard.
1 long + 9 short	Error reading data from ROM.
2 short	Minor faults
3 long
Continuous sound	The power supply is faulty.

AMI BIOS signals

Signal type	Decoding and what it means
2 short	RAM parity error.
3 short	Error in the first 64 KB of RAM.
4 short
5 short	CPU failure.
6 short	Keyboard controller error.
7 short	Motherboard failure.
8 short	Video card memory failure.
9 short	BIOS checksum error.
10 short	Cannot write to CMOS.
11 short	RAM error.
1 dl + 1 cor	The computer's power supply is faulty.
1 dl + 2 cor
1 dl + 3 cor	Video card operation error, RAM malfunction.
1 dl + 4 cor	No video card.
1 dl + 8 cor	The monitor is not connected, or there is a problem with the video card.
3 long	Problems with RAM, test completed with error.
5 cor + 1 dl	There is no RAM.
Continuous	Problems with the power supply or PC overheating.

Phoenix BIOS Signals

Signal type	Decoding and what it means
1-1-4	CPU error.
1-1-4	Cannot write to CMOS. The battery on the motherboard is probably dead. Motherboard failure.
1-1-4	Invalid BIOS ROM checksum.
1-2-1	The programmable interrupt timer is faulty.
1-2-2	DMA controller error.
1-2-3	DMA controller read or write error.
1-3-1	Memory regeneration error.
1-3-2	RAM test does not run.
1-3-3	The RAM controller is faulty
1-3-4	The RAM controller is faulty.
1-4-1	RAM address line error.
1-4-2	RAM parity error.
3-2-4	Keyboard initialization error.
3-3-1	The battery on the motherboard is dead.
3-3-4	Video card malfunction.
3-4-1	Video adapter malfunction.
4-2-1	System timer malfunction.
4-2-2	CMOS termination error.
4-2-3	Keyboard controller malfunction.
4-2-4	CPU error.
4-3-1	Error in RAM test.
4-3-3	Timer error
4-3-4	Error in RTC operation.
4-4-1	Serial port problem
4-4-2	Parallel port problem.
4-4-3	Problems with the coprocessor.

In my practice, it most often beeps due to RAM. The fix is quite simple: take out the RAM, clean the contacts and firmly insert it into place until the fasteners click. As for the other sounds, there is a lot of information on the Internet for each of these errors that is easy to find. I see no point in describing it, the article is already cumbersome.

The computer won't turn on at all

If you press a button and the computer does not turn on at all, i.e. no emotions, sounds, squeaks, no indicators light up - first check the power supply. If you have changed the outlet, tightly connected the power cable and there is still silence, remove the PC cover and turn it on. If it spins, then scroll down the page, but if nothing happens, we will check for functionality.

How to check the power supply

Unscrew the power supply from the computer case and disconnect all wires. Remove the power supply from the computer.
Take a paperclip and break it in half to make a letter U.
Take the thickest wire harness with the largest hole (that you disconnected from the motherboard) and insert a paperclip to close it black And green the wire:

Connect the power cable to the power supply and plug it into a power outlet. Important!!! Do not hold the power supply in your hands and make sure that all wires are disconnected from the motherboard. fees.

Now one of two things: the power supply will either hum and work, or there will be silence. If the power supply starts working by shorting the black and green wires, then the problem is in the motherboard; if there is silence, then you need to buy a new power supply.

Self-repair of power supply: you could write about how to restore the power supply, but I’m more than sure that if you could do it, you wouldn’t be reading this. In addition, often after improper repair of the power supply, other components burn out. I strongly recommend buying a new one (it’s not expensive) and saving your computer and your time.

The computer does not turn on, but the system unit fans are working

It’s not a pleasant situation in which almost everything is unclear. This symptom may hide many breakdowns, which will have to be sorted out one by one to understand what exactly happened.

PSU is faulty. Perhaps it provides tension, but it is not enough. First, open it up, make sure that there are no traces of burnt parts, liquid on the board from capacitors, and check the capacitors so that they are not swollen as in this photo:

If you find them, most likely this is the problem. The power supply works, but not at full capacity and the computer lacks this. To make sure, take a working power supply from someone and install it for yourself to make sure.

Video card failure. Your computer is running at full capacity i.e. Does it sound the same as before the breakdown? If yes, connect the speakers to the computer, turn it on and wait for the system greeting (OS boot sound). If this happens, you see that the PC is working, but there is simply no image, this means that the video card is faulty.
BIOS crashed. This happens, it even happened to me. To try to fix it, turn off the computer, remove the cover, take out the battery (the size of 5 kopecks, similar to the battery in a scale) and wait 20 minutes. Then insert it into place and turn on the computer. If it helps, the BIOS has crashed and I would recommend checking for updates for your motherboard. fees.
The problem is in the components. Almost always in such cases, the speaker tells you what exactly is wrong with the computer, but it is possible that you do not have one or it is not working properly. Disconnect all components one by one until you find the one with the problem.

Start with the video card. If you have an integrated one and an external one, try removing the external one and connecting the monitor directly to the motherboard. If that doesn't help, remove the RAM and then try inserting it into another slot. Disconnect the HDD, if this is the case, the image will appear.

Checking the motherboard. Do you see a large chip on the board (like a box of matches), perhaps an aluminum radiator is installed on it?

This is a chipset worth checking out. Turn on the computer and hold this chipset with your finger for 3-5 minutes. If it gets very hot, it means the bridge has burned out. I do not recommend soldering it, because the computer will not work for a long time and after a short time the breakdown will recur.

You can also watch the video, it’s quite possible that I missed something, and I haven’t encountered anything at all:

If nothing helps, it is more than likely that your motherboard is burned out. As I said above, there is no need to solder it, because the next breakdown is not far off.

The computer does not turn on the first time

Most likely, you have swollen capacitors somewhere in your power supply or on the motherboard (see example picture above), which is why this is happening. If I'm right and you find them, immediately turn off the computer and resolder them or take the PC to a service center. Until your computer does not turn on the first time, and then the entire motherboard may burn out!

Reason #2 – bad contact. Open the computer, disconnect everything you see and reconnect everything in place, making sure that everything is connected well. It is also advisable to wipe the contacts with alcohol, then wipe them dry and insert them back.

That's all, I hope I helped you, and you figured out your problem without going to the service center.