Why the computer does not turn on - the first step towards finding out the cause

The most common BIOS sound signals:

Award or Award - Phoenix BIOS

• 1 long beep and 3 short beeps - the video card is not found or is not working
• Long repetitive signals - RAM not found or not working

AMI Bios (American Megatrends, Inc)

• 2, 3 or 4 short beeps - problem in RAM
• 5 short beeps - the processor may be defective
• 1 long, 3 short beeps - video card malfunction

Phoenix Bios

• 3 very short and 4 short signals - the video card is faulty
• 2 short beeps and 1 long - memory failure.

Let's outline the main reasons why the computer does not turn on, and we will go along the path of identifying the source of the problem:

1. Power supply problems 220V
2. Power supply defective
3. The battery has run out
4. A lot of dust
5. Power button
6. Defective motherboard

Someone may say that what is proposed below is superfluous, but personal experience suggests otherwise. If your laptop or computer does not turn on, check the connection of the cables (not only the plug plugged into the outlet, but also the connector connected to the system unit), the operability of the outlet itself, and other things related to the connecting cables (possibly, the operability of the cable itself).

It happens that everything is in order with the outlet, but electricity does not reach the computer due to poor contact of the power cable. You need to try to pull out the power cable from the system unit and insert it back tightly.

Also, most power supplies have an additional ON-OFF switch (usually found on the back of the system unit). Check that it is in the "On" position (Important: do not confuse it with a 127-220 Volt switch, usually red and not accessible for simple finger switching, see photo below).

If, shortly before the problem appeared, you cleaned the computer from dust or installed new hardware, and the computer does not turn on "at all", i.e. there is no fan noise, no light from the power indicators, check the connection of the power supply to the connectors on the motherboard, as well as the connection of the connectors on the front panel of the system unit.

Power supply defective

If there is no known working power supply unit at hand, then you can try to check the existing one. This requires a voltage tester. You can measure the voltage only if at least the lights come on when the computer is turned on. To do this, we take any power connector and measure the voltage: between any black and red wires there should be 5V, and between black and yellow 12V.

If the voltages differ (a deviation of 5-7% is allowed), then definitely look for a new power supply. If it is not under warranty, then you should not contact its repair.

When some power supplies wear out, the effect of "sticking" of the internal protection can be observed. Try unplugging the power cable and leaving the computer unplugged for 5-10 minutes, then plug the cable back in and try turning it on. If the computer still does not turn on, and there is no other power supply unit at hand, let's go over other points why the computer does not turn on. You will also be interested in Free programs for repairing flash drives and How to identify unknown devices in Windows.

If your computer makes a noise when you turn it on, but the monitor does not turn on

One of the most common cases. Some people mistakenly believe that if the computer is buzzing, the coolers are working, the LEDs ("lights") on the system unit and the keyboard (mice) are on, then the problem is not in the PC, but simply the computer monitor does not turn on. In fact, most often this indicates problems with the computer's power supply, RAM or motherboard.

In general (for an ordinary user who does not have additional power supplies, motherboards, RAM cards and voltmeters at hand), you can try the following steps to diagnose the cause of this behavior (before the described actions, unplug the computer from the outlet, and to completely de-energize press and hold the power button for a few seconds):

To summarize, if the computer turns on, the fans work, but there is no image - most often it's not the monitor or even the video card, but the main reasons: RAM and power supply.

Problems with components or cables

Here you need to work with the method of exceptions. The problem may lie in any components inside the system unit: RAM, video card, hard drive, cables, expansion cards (TV tuner, sound card, external controllers). To begin with, we leave only what is necessary for the initial start of the computer, and turn off everything else. Those. we leave the processor with a fan, RAM, video card (if not built-in) and keyboard connected to the motherboard (check if its connector is firmly inserted). We try to insert the RAM into another slot or leave only one bar (if there are more of them). If the computer turns on, then we connect the hard drive and see if the operating system is loaded. If so, we connect the devices one at a time and thus find the culprit. By the way, the guilty device may just work, but the whole problem lies in the cable or loops. Therefore, they must also be taken into account. See also Troubleshooting Recorder and How to speed up computer startup and shutdown.

Low battery

Every motherboard has a small 3V lithium battery. It supports volatile CMOS memory, which stores BIOS settings. On computers that have worked for 3-5 years, or have been in warehouses for a long time, the battery runs out and the settings are lost. It's easy to see if the time is reset every time the computer is turned on. Sometimes an error occurs at startup and the BIOS asks to enter it and save the settings. But in some cases, the computer may not turn on at all or turn on every other time. Checking the battery is not difficult if there is a voltage tester. If it is not there, then the battery just needs to be replaced. They are sold at any computer store.

Power button

One of the reasons why the computer does not turn on is the "Power" button for turning on the computer. If it does not close the contacts well, then it is logical to assume that the computer will not turn on. Removing the button is easy. To do this, you need to find on the motherboard the place where the wires are connected from the front panel of the case, and there you find the “Power” connector. The connector must be pulled out, and the two contacts must be carefully closed with a screwdriver. If the computer still does not turn on, then move on. You will also find it useful Tips for tuning and optimizing Windows and How to speed up the system by 50% without third-party programs.

Defective motherboard

The last option, the most disappointing. After all, the motherboard will most likely have to be replaced with a new one, and this will cost a pretty penny. I think you will want to take a newer board, and this is a new processor, and possibly RAM, and then look and the video card will tighten, and after it the power supply, in short, change the entire computer. Please note that if you change the motherboard to another of the same level, it should contain:

• the same processor socket (socket)
• the required number of RAM slots, and of the same type (DDR, DDR2, DDR3 ...)
• interface for connecting an existing hard disk (IDE, SATA)
• a sufficient number of expansion slots for existing cards (PCI, PCE-Express)

If the new motherboard will have a different set of system logic, then you may have to reinstall the operating system.

Waking up in the morning, with the usual push of a button, you turn on your PC, and ... nothing happens. You can panic, or start calling all your acquaintances who "seem to be a programmer or a designer ... But you have to understand computers!", Or you can try to figure out what's the matter yourself. Possible reasons why the computer does not turn on and what to do about it, we will try to consider in this article.

An important amendment: we will consider situations only when the computer does not turn on at all

1. after pressing the "Power" button, nothing happens at all
2. the computer tries to boot (the lights come on, the fan starts working), but shuts down immediately
3. the bulbs are working, a squeak is heard, but the computer does not boot.

The computer does not start - we are looking for the reason

The very first and seemingly trivial step is to check the network connection and the operation of the cables. The advice may seem silly to someone, but in fact, at this stage, sometimes up to half of the situations are cut off. It is worth checking if the cable has come off, the outlet is working.

These tips universally apply to other related devices: mice, printers, speakers, keyboards.

Checking the cable is just pulling it out and it's better to plug it into the socket. If the wire is seemingly of poor quality and weak, of course it is worth trying a new one for the sake of checking - at least for the cable from the monitor. And be sure to make sure that the button on the power supply (usually located near the power connector) is in the correct position.

The main thing is not to confuse it with the input voltage switch button.

It is necessary to change the input voltage level between the American 127 V standard and our 220-volt one.

It is important that the outlet is powered by 220 volts - the functionality of the outlet can be easily checked by connecting other devices. If many consumers are connected to a single power source by means of tees, the load may be exceeded.

In such a situation, it is advisable to disconnect the rest of the devices and check if the PC turns on if it is connected alone.

If the voltage exceeds or, on the contrary, does not reach the required rate, the machine may burn out or simply not turn on. There are special devices for testing voltage, but you can determine the level without them, if there is an ordinary light bulb... If the voltage is insufficient, the light will shine weakly. If the voltage is too high, then the opposite situation is observed, the lamp shines brightly, after which it can burn out.

If the computer beeps and does not turn on, we can try to determine the cause of the failure by the sound.

It is advisable to once again make sure that the speaker is correctly connected to the motherboard - perhaps the computer wants to give you a signal, but you do not suspect.

This problem is especially relevant for users who have never heard such squeaks from their own PC before.

Problems on each BIOS version may sound differently. They can be higher or lower, longer or shorter, the combinations of signals also may not coincide. Let's consider some options.

For example, on one of the BIOS versions you can hear the following options:

• triple long / triple long - single short: motherboard problems.
• Double short: PC does not see the monitor.
• Short with repetitions / long without stopping: breakdown of the power supply, or a malfunction of the motherboard.

In another version of BIOS signaling can be as follows:

• Triple long: problems with the input device controller.
• Long-term without stopping: power supply failure.
• Single long - double short: video adapter not detected or disabled
• Long or short signals with constant repetitions: the RAM module is not detected or is disabled.

In the third considered version of BIOS there is an important feature. Here the signals are built according to the system using several beep sequences. Older versions will have three sequences, and newer versions will have four.

• Long signal with constant repetitions: motherboard malfunction.
• Long non-stop: broken or disabled fan.
• Single - single - double: CPU failure, replacement is desirable.
• Triple - triple - quadruple: video adapter memory initialization is missing
• Triple - quadruple - single: the computer does not see the monitor, or else fixes its error.
• Triple - double - quadruple: no initialization of the input device controller.

Consider another version of BIOS, the signals in which will sound as follows:

• Sevenfold short: the motherboard is broken
• Five-fold short: PC has detected a CPU malfunction
• Single long - four times short: the video adapter is not detected, or its error is noted.

In order to decipher what your computer is beeping about, you should know from which manufacturer of your motherboard's BIOS.

General list of possible problems:

1. system voltage problems
2. the motherboard battery has run out
3. power button malfunction
4. connection or parts problems

If there is a fault in the power supply

Perhaps the most unpleasant problem can befall your PC if the power supply itself is broken or burned out. Unsurprisingly, in this case, the computer refuses to turn on. Moreover, such an event may cause damage to other connected components.

You can check the existing power supply using a voltmeter, and for a deeper diagnosis, you will also need an ohmmeter.

But this method is suitable only for situations when the computer does not boot, and the lights are on at the same time. To check, the power connector is taken and the voltage is measured on it. This indicator between the red and black conductors should be 5 volts, between the black and yellow wires - 12 volts.

You can try to correct the problem by unplugging the power cord so that the computer remains unplugged for a while. Then return the cable back and make a test run of the computer. There are situations when after long use, from wear and tear, the effect of "sticking" is created in the inner protection. If this did not help and still failed to start the computer, proceed to the next points.

Yes, oddly enough, ordinary dust and dirt inside the computer can greatly affect its operation and be one of the reasons why the computer does not turn on... In order to test this hypothesis, it will be necessary to clean the insides of the system unit (and the components would not hurt), it will not be superfluous anyway.

Cleaning should be done with a mini-vacuum cleaner and a brush, preferably not with cotton wool or paper disks, so that particles of fibers do not remain inside.

The proposed order of priority is as follows:

• We clean the contacts of the RAM and boards.

To do this, the computer is disconnected from the network, the memory is removed. Many experts say that contacts can be cleaned with a regular eraser, someone uses a cotton rag the old fashioned way.
Attention: do not wipe the entire memory strip, but only the contact track!

This is required in order to remove the existing oxidation, which can interrupt the contact between the RAM and the motherboard. After that, you can walk with a brush, or a brush with soft bristles, so as not to damage the microscopic parts.

• We do the same with other cards, for example, a video card.
• We check the processor coolers for contamination.

We clean, see if the fans are spinning. Due to contamination of the fans, the cooling system may not work well, in which case the computer will overheat and unexpectedly restart itself.

Inoperative battery

All motherboards have a small coin cell battery. It is often called "battery for BIOS", as it supports CMOS memory, which, in turn, stores PC configuration parameters (BIOS Setup settings), as well as the system timer. Motherboards use lithium batteries that differ in capacity and thickness. On average, their service life is 2-5 years, because if the computer has been in use for such a period, or even has been in a warehouse, the battery runs out. And along with it, the settings are lost.

Often times, PC owners discover this because each time you turn on, the time settings get lost(as we indicated above, the battery maintains a store of the system timer settings).

Sometimes problems with the battery are detected in other ways, through system messages, failure to launch some programs, even problems with the work inside the browser. But to the extent that the computer does not turn on, or turns on every other time.

The easiest way to check if the battery is the case is by buying a new one. They are not expensive, in the range of 50-100 rubles. If you can't buy a battery of the required type yet, but you have a voltage tester (voltmeter, multimeter) at hand, you can check the voltage. 2.7 - 3V is the normal voltage for the CMOS BIOS to work.

Such a "test" was recently bought by our IT department. The most Chinese, no name for four dollars. Here is her test drive, and I want to present to you today using the example of a situation when the computer does not work. I also want to say that such devices can cost forty dollars, while having various additional functions and having a certain "brand". But, as they say, what we have is what we test :)

First - briefly about the abbreviation "POST" (Power On Self Test), it can be translated as - self-test after switching on. This is a set of sequentially executing microprograms-tests, "wired" in the non-volatile memory CMOS BIOS. You can get acquainted with what a BIOS is and what its function is. You probably noticed that after turning on and immediately before loading the operating system, one short beep is heard from the system speaker? If the computer does not work, then, accordingly, it is not distributed :)

Such a signal "tells" us that the system has passed the entire set of post tests successfully and is ready to work. The POST sequence, in fact, consists of a couple of dozen separate tests designed to test all the main nodes of the system for their correct operation. At this stage, processor registers, RAM (its first 64 kilobytes), graphics adapter, drive controllers, COM and LPT ports, etc. are checked. In the end, the whole thing ends with a beep and the transfer of control to the operating system loader.

If a failure occurs at any of the testing stages, it usually bursts out with a series of beeps. Depending on the manufacturer of the motherboard Bios, you can even hear by ear that you can determine why the computer does not work and with which of its nodes there are problems.

But this is the ideal. In reality, it happens that in the event of a malfunction from the system speaker, either no sounds are heard at all, or such trills that are not described in any manual :)

So - POST board for troubleshooting your "iron friend" :) This is how the package of its delivery looks like in our case:

Let's figure it out. The entire package can be presented like this:

1. diagnostics board (fits into PCI slot)
2. book with decryption of all stop codes POST
3. USB cable providing power

It's time to remember what we mentioned at the very beginning of the article (about catching initial initialization error codes). This is exactly what these devices are doing. If any test is unsuccessful, its alphanumeric code is displayed and the diagnostic post does not go further. Do you see the two 7-segment cells (in the upper right corner) of the device? They display the numerical values ​​of errors.

The booklet that comes with the board contains a description of all POST codes for different BIOS manufacturers. This is convenient and saves us from having to search the network for error codes for different chip manufacturers every time and guess why the computer is not working? And here - everything you need is presented in the form of one pivot table.

An additional USB cable is needed only if we insert our board directly into the LPT port (in our model there is such an opportunity) then we connect one end of the cable to it, and the other to the USB connector of the pc. Thus, providing her with electrical power. But this is not necessary at all, and modern "machines" are often no longer equipped with a parallel port.

I think that now (after mastering the required minimum of theory) it's time for us to practice. Real situation: the computer does not work, it does not give any sound signals. Let's check how our "tester" will cope with its task and will it help us diagnose the malfunction not only by ear, smell, touch, but also to approach it more professionally, understanding WHAT exactly we are doing? Do not be content with the successive replacement of components, in the hope that in this way we will surely "stumble" on a malfunction.

Agree - sometimes you want to look like a professional in your field! :)

So, let's describe in detail everything that we did: Place our board in the PCI slot and press the power button. On its sensors, various numbers begin to flash quickly, signaling the successful passage of one or another test from the POST set. The number "29" appears on the cells, the test stops at this, the computer shows a black screen and does not give any sound signals.

Pay attention also to the row of LEDs that show the presence of voltage on the motherboard along the main lines (3, 5 and 12 volts), as well as the indicator of voltage supply to the clock generator (clocker), which is denoted by the abbreviation "CLK". But all this is additional information. We are now interested in the number "29" and what does it mean in our specific situation?

One simple thing to remember - for different BIOS manufacturers, the same post codes will mean different errors. From this it follows that it is enough for us to unambiguously determine the bios manufacturer, and then just look into our book and see what error is listed under a certain number (in our case, number "29").

Let's dwell on this point in more detail (since this is the key point in this diagnostic option) and consider all possible options for how this can be done. For example, for the Windows environment there are a lot of diagnostic utilities that, along with other data, show us the manufacturer, version and serial number of the BIOS installed on our site.

I suggest you use a small utility "", which does an excellent job with this task. You can download it from the link above. The program does not need to be installed, you just need to start it and press the "Get BIOS Info" button in the window that appears.

The line "BIOS Type" says "American Megatrends" - this is the firmware from AMI. Also pay your attention to the logos of bios manufacturers, presented in the left part of the screenshot. Let's take a closer look at them:

These are the three main firms that develop BIOS routines for computers: American Megatrends (AMI), Phoenix, and Award.

The second possibility to determine the manufacturer of the software part of the microcircuit is to view the system boot screen. As a rule, the upper part contains all the information we need.

As you can see, this is already an Award BIOS and, as we remember, error codes (both beeps and their alphanumeric values ​​on the POST diagnostic board) will differ from the competitor.

I want to voice a small nuance. Often, the initial boot window of the system is hidden by a full-screen image of the motherboard manufacturer or by an advertisement for a specific model of it. In any case, we do not see the information we need, but we see this very picture when loading.

In order to disable it, go to the BIOS (usually in the BOOT section), then - Boot Settings Configuration (boot settings). Again, depending on the manufacturer, the labels may differ, but the essence is the same.

We go to the section indicated in the photo above and look for the Full Screen LOGO inscription in it and set it to the “Disabled” position.

We save the settings, reboot and instead of an unnecessary picture we see the information we need :)

In general, when asked what to do if the computer does not work? You can give a completely unequivocal answer - to diagnose! Those. - bit by bit collect data that will help us in solving the problem.

In this regard, I cannot but say a few words about one more source of this information, which we need to periodically pay attention to. This is a one-line entry located at the very bottom of the boot screen and is, in some (conditionally encrypted) form, the motherboard identifier. In my case, it looks like this:

In this case, in one of the line segments, we see a direct indication of its exact model - "M2NPV-MX".

Why do we need this at all? Well, for example, you cannot open the system unit to view the necessary information (it is under warranty). Then just carefully read this line or drive it into the Internet search engine and try to navigate in this way.

Clue: if you do not have time to read something from the screen during boot, then you need to press the "Pause" key on the keyboard and the boot will stop.

In order to continue, simply press the "Enter" key or the space bar.

If we are already analyzing the situation when the computer does not work, then let's take a deeper look at the possibility of examining it without opening the system unit itself and without loading the operating system. For this purpose, I recommend you another very useful utility. It is called "" (you can, of course, download it from the link). Even in demo mode, it will show you all the basic information about the hardware.

Download the archive with the program, unpack it and write the iso image in it to a blank disk. This will be a boot disk, starting from which you can view the information we need. After launching, we will see the following picture:

The program scans the equipment. Then it provides us with the result of its work:

As you can see, there is quite detailed information on the processor and motherboard of the computer. But, since we are still interested in the possibility of determining the manufacturer of the BIOS, then pay attention to the underlined line. In our case, this is Phoenix Bios. I want to emphasize that this is data from our real situation. The computer did not actually work.

If, for some reason, you are unable to determine the manufacturer of the bios by all the methods described above, then all that remains is to remove the side cover and carefully look at the marking of the Bios microcircuit itself. In our case, it looked like this:

Usually we are interested in the first row of numbers. Having driven this data into the line of any search engine on the Internet, we can (with a successful coincidence of circumstances) find out the information we need.

But let's get back to our case. Otherwise, the article is already big :) We found out that the testing procedure stops abnormally at code "29" and that the manufacturer of the BIOS of our motherboard is Phoenix.

We just have to open the booklet attached to our kit and find the required error description. Here is an excerpt from such a section of the manual:

Here is the description of the problem: "Initialize POST Memory Manager". I think you can guess that the problem is memory related, but let's check this data! We drive this inscription into the Google search bar. We quickly find the description we need:

Indeed, we are convinced that we have a problem with RAM (RAM - random access memory).

Well, if the computer doesn't work, it doesn't matter! Let's fix it! Let's do it like this: extract it from our "patient" and place it in the working configuration on the compatible one on the connectors. Then, we "take" the "tool" corresponding to this case - the program for diagnostics of the RAM "Memtest" and boot from the disk created by it. When passing one of the tests, we observe the following picture:

According to one of the previous articles devoted to, you remember that the red color indicates errors of reading-writing memory.

What is left for us to do? That's right - replace the "broken" memory module with a working one and see what our post board will show this time?

The value "FF", in most cases, signals us about the successful completion of the entire POST test sequence and the transfer of control to the operating system loader.

Naturally, this PC is now functioning properly, and as a result of this repair, another article appeared on our website, which, I hope, will help you approach diagnostics from a more scientific position. After all, now, if the computer does not work, you know exactly what to do :) On this - all the best and until the next articles!

Let's consider the main causes of the problem when the processor is not working, the need for replacement or repair. How to determine what happened to the chip by the BIOS signals?

from 290 p. RUB

Despite the seeming simplicity of the device, the computer is the most complex system. Its most common chip, measuring 10x10 mm, can perform a fantastic amount of computing operations, ensuring reliable and stable PC operation.

However, if your computer does not have a processor, then you will not be able to take advantage of any of its capabilities.

The device simply won't boot. But how to determine what exactly is the cause of the breakdown? Is it really this element of the PC that is the cause of certain manifestations of malfunctions? What if the processor is not working? We will talk about this today.

How to identify a breakdown?

Immediately, we draw your attention to the fact that if not all processor cores are working on your PC, this is not a guarantee of malfunction!

They can simply be disabled, in order to activate them, you need to find the appropriate options in the operating system.

But now that's not about that, let's analyze the characteristic signs that directly tell us that the processor is not working. There are three main ways to identify a problem:

• By means of sound signals;
• By inspecting the motherboard;
• By connecting the processor to another PC.

The first way is preferable because It is not recommended to open the system unit yourself if you do not have the appropriate skills. It is important to know that the motherboard is equipped with a special speaker, and its software (BIOS) is capable of giving signals when a malfunction is detected.

However, if your AMD or Intel processor is not working, or depending on the motherboard manufacturer, the signals may differ. Therefore, be sure to arm yourself with instructions, where there are all the necessary decryptions.

If it is not possible to hear sound signals, it is necessary to open the system unit. If your Intel or AMD processor is not working due to burnout, it will be easy to recognize the problem. The appearance of the chip will immediately grab your attention. It may notice melting, darkening, smell burnt.

The only way out in this situation is to replace the chip, and possibly the motherboard. If there is no visual damage, you can try connecting the processor to another PC, but you need to be very careful here!

A defective CPU can damage the motherboard of another computer, so leaving a PC with a diagnosed chip turned on for a long time is strictly prohibited.

Sometimes there are situations in which, despite the complete external serviceability and the absence of suspicious signals, the processor does not work. It seems that you have already made sure that there are no serious problems, but the computer stubbornly does not want to work correctly. Are you sure you haven't missed anything? This means, most likely, the problem lies in the lack of power supply to the chip, which is also quite common.

If your processor power is not working, then you need to find out the cause of such problems. As a rule, the following phenomena lead to them:

1. Damage to the power supply;
2. Problems with the motherboard;
3. Lack of proper contact between the PSU and the motherboard;
4. Inattention of the PC owner.

The last point should be dwelled on in more detail, since such troubles often haunt users who repair and replace components on their own.

The new processor you just installed is not working?

Let's find out the reasons why the computer does not turn on: the speaker does not beep or beeps. That is, when, when the power button is pressed, the computer does not show any signs of life, or if it does, then they are not what we would like. The reasons can be as simple as there is no power supply, or complex - a device (memory, HDD, etc.) is out of order.

Before we start dealing with this problem, you need to check the simplest one:

• Is there a plug in the socket
• Is the surge protector turned on
• Isn't the light off?
• Pay attention to the monitor. The computer may be turned on, but the monitor itself is turned off through the button or there is no power. Is a monitor cable (VGA or DVI) connected?

Of course, the above is a must for you to see what is happening on the computer, but sometimes users do not pay attention to these moments, thereby creating other complications that are more time consuming.

220V does not come

Power may not come to the computer if:

No voltage at the input- for example, the socket is faulty. It's easy to check - connect from another outlet, or plug a known working electrical appliance into this outlet. For example, a kettle, hairdryer or a surge protector with an indicator. Usually, it is the power filter that I determine whether the outlet is working or not, if it is on, then everything is in order with it. We think further.

Behind the system unit, there is a special button for the power supply... You need this button to be in position "1" - on, if "0" - off. If this button is absent, then you do not take any action at this stage.

The power cable may come off- wiggle it, or pull it out and reconnect.

The cable itself is faulty- ring it with a tester or indicator If you do not have these tools at hand, you can take another power cable and replace it during the test. If the computer turns on, then the problem was in the power cable and you just need to replace it (the cost of the cable is about 100 rubles.)

So, we made sure that everything is in order with the cable, let's move on.

Monitor and video card

If you pressed the power button of the computer, it made a noise - turned on, then you need to check the cables from the system unit to the monitor. Very often the cables leave the monitor, in this way you do not see anything on the monitor, but in fact the computer is turned on and working.

There should be a cable from the system unit that transmits the image to the monitor and a cable from the surge protector that supplies energy. If everything is in order with these cables, then pay attention to the video card (if you have it external).

If the video card is faulty, the monitor will display a "No Signal" pop-up window. To begin with, it is worth checking the VGA or DVI cable, this is what kind of connection you have. Check if it is firmly inserted, if the pins of the contacts are not bent. Pull out the video card and clean the contacts with an eraser.

If all else fails, try to pull it out and switch the cable to the integrated video card in the motherboard, if there is one, of course.

Iron malfunctions

It all starts with the power button, and that's where we'll start. Now you need to open the lid of the system unit and see if there are any breaks in the wires. Be sure to check it out!

BIOS signals

When you press the power button, the POST self-test program starts and if it fails (hardware not connected or bad contact), the download simply stops, and the speaker (speaker) starts emitting beeps. Their sequence depends on the BIOS. From them, you can determine the source of the error.

You will always find these signals in my article: "". If you find out which device is faulty, try replacing it with another, borrow from friends or neighbors. In the event that everything works, you can buy this component.

Broken wire for Power button

From my own experience, I can say that this problem is rare, but it should not be discarded to the last stage of testing. If you have a broken wire from the Power button, then you will not turn on the computer and therefore make sure that everything is in order with the wire that goes from this button.

I once tested a computer that didn't want to turn on. He seemed to have done everything he could, but there was no reaction from the computer. Then I removed the front cover from the system unit and found a broken wire there. In a couple of minutes I connected it, wrapped it with electrical tape and it turned on unquestioningly. Apparently before me, someone had already disassembled it and accidentally clamped this wire, thereby tearing it when closing the front cover.

So, if you removed the cover of the system unit, then do not be too lazy to open the front cover.

Power Supply

Now there is a choice to buy a power supply unit and of course people buy what is cheaper, because they think that this will not affect the operation of the computer in any way. If you buy a cheap Chinese power supply, then we can say that your computer will live next to a powder keg, which can explode at the most inopportune moment.

Note: it is better to save money, for example, on a computer case and buy a normal power supply.

The power supply is a very important component in a computer, as it supplies energy to all the devices in the computer. Therefore, if your computer does not turn on - a black monitor screen, then the power supply may be the cause of this breakdown.

In this section we will experiment, but if you have a spare power supply or borrow for a while from another computer (neighbor or friend), then it is better to immediately connect another power supply to your computer. This way you will save your time. At a minimum, its characteristics should be the same as yours, or better - it will be most correct. You can find all the data on the power supply on the sticker on it.

The very first thing to do is to unplug the power cables from: floppy, floppy, and hard drive. Then disconnect the video card, if you have an external one, and remove the RAM from the motherboard. Then try to turn on the computer. If the computer beeps, it turns on, then turn it off, connect one device, then turn on the computer, if it turns on, then connect another device, etc. You must understand which device was preventing the computer from turning on.

To test the power supply, you will need a voltage tester. Eh, sighed users who do not have this device. I understand you, but still there are people who bought it, since the breakdown of electronics is not uncommon. We take a tester and any power connector that comes out of the power supply and measure the voltage. There should be 5V between black and red, and 12V between black and yellow.

If, during testing, the power supply voltage differs from the numbers that I mentioned above, then it’s time to go to the computer store for a new one. By the way, there are permissible deviations when measuring voltage. Approximately 5% is allowed. If you have, for example, 11.9, then everything is in order with your power supply and you need to look for the problem elsewhere.

If you want a modern power supply, then buy 400 - 500 watts. Take the middle one.

Often problems arise due to the discharge of the battery, which is located on the motherboard. If you recently had cases when the computer got out of time, then most likely you need to change the battery. The price of the battery is small and you can get it at any computer store.

To check the battery, remove it and check the voltage in it or simply replace it.

If the computer beeps and does not turn on, then it is possible that the memory sticks are faulty. There is also a small chance that the computer is not making any sounds due to the speakers being inoperative. Pull the memory out of the slot on the motherboard and clean the contacts with an eraser. Put them back in place and try to turn them on, if it still does not turn on, pull them out again and stick in one by one. Perhaps one ruler is faulty.

If the motherboard has other connectors that you did not use to connect the RAM module (s), then try using them.

BIOS

So, another option is what to do if the computer does not turn on. If you have recently made any changes in the BIOS, then now you need to return the default settings. Of course, the question is brewing how to do this if you do not see anything?

You need to disconnect the battery from the motherboard, connect the computer power and press the power button several times. Then leave the computer without a battery for 20-30 minutes and then plug it back in.

If some inscriptions appear on the monitor screen when you turn on the computer, but Windows does not boot, then you can go into the BIOS and find a function to reset the settings to factory defaults. After that, do not forget to save the changes made to the BIOS by pressing the F10 button (usually).

Motherboard

So we come to the very last section of this article, as well as the most uncomfortable one - the motherboard. If your motherboard breaks down, then repairing it can add up to a tidy sum.

If you are going to repair it, then think, but does it make sense? Sometimes its repair can exceed 50% of the cost, and then the question arises, is it not easier to buy a new one?

So that you do not have a question - why the computer does not turn on and what to do in this situation, once a year carry out preventive maintenance with it - clean the dust and replace the thermal paste once every 2 - 3 years (approximately). By the way, the dust in the computer greatly interferes with the operation of the computer, and since you have opened the system unit, then clean everything from the inside.