The phrase in the title is often heard and read in user comments on this site. This manual describes in detail all the most common situations of this kind, possible causes of the problem and information on what to do if the computer does not turn on.
Just in case, I note that here we are only considering the case if, after pressing the power button, no messages from the computer appear on the screen at all (i.e. you see a black screen without previous motherboard inscriptions or a message that there is no signal) .
One of the most common cases. Some people mistakenly believe that if the computer is humming, the coolers are working, the LEDs (“light bulbs”) on the system unit and keyboard (mouse) are glowing, then the problem is not in the PC, but the computer monitor simply does not turn on. In fact, most often this indicates problems with the computer's power supply, RAM, or motherboard.
In the general case (for regular user who does not have additional power supplies, motherboards, boards at hand RAM and voltmeters), you can try the following steps to diagnose the cause of this behavior (before the described actions, turn off the computer from the outlet, and to completely turn off the power, press and hold the power button for several seconds):
To summarize, if the computer turns on, the fans work, but there is no image - most often it is not the monitor or even the video card, the “top 2” reasons: RAM and power supply. On the same topic: .
The computer turns on and then turns off immediately
If immediately after turning on the computer turns off, without any squeaks, especially if shortly before it did not turn on the first time, then the reason is most likely in the power supply or motherboard (pay attention to points 2 and 4 from the list above).
But sometimes this can also indicate malfunctions of other equipment (for example, a video card, again, pay attention to point 2), problems with cooling the processor (especially if sometimes the computer starts to boot, and on the second or third attempt it turns off immediately after turning on, and shortly before this, you were not very skillful in changing thermal paste or cleaning your computer from dust).
Other possible causes of failure
There are also many unlikely, but still encountered in practice, options, among which I have encountered the following:
- The computer turns on only if there is a discrete video card, because The internal one has failed.
- The computer turns on only if you turn off the printer or scanner connected to it (or other USB devices, especially if you have them recently).
- The computer does not turn on when a faulty keyboard or mouse is connected.
If nothing in the instructions helped you, ask in the comments, trying to describe the situation in as much detail as possible - how exactly it does not turn on (what it looks like to the user), what happened immediately before and whether there were any additional symptoms.
If the computer does not turn on, this does not mean that something in it is necessarily broken or that you need to call a specialist, open the case, etc. The computer does not turn on for other reasons. Let's, according to tradition, look at this point using several examples from practice.
I’ll make a reservation right away: everything that will be described below should be considered as the simplest version of the situation when the computer does not turn on. It is very likely that the reason for this may lie in something else:, or something else. If you have, then we also have an article for this case on our website.
Here I want to talk about the fact that behind all these harsh “hardware” problems, people sometimes do not see the most basic and obvious things, and if the computer does not turn on, they can do a lot of unnecessary and unnecessary work.
First, let's look at the most common case when the computer does not turn on, which plunges the average user into a catatonic stupor and forces him to press the “power” button to no avail, and then call the technician :) This happens at our work regularly when there is a sudden power outage.
The master comes, puts one hand behind the system unit, does something there and “the car starts.” The user is happy and happily distributes inexpensive candies and cookies :)
At certain intervals after The lights go out and the computers won't turn on.. Let's figure out why this happens. At the moment of a sharp drop in voltage, the power supply protection is triggered. The voltage drops quickly, but due to the capacitors in the unit itself, it does not drop quickly enough for the protection not to react.
Note: A high-quality power supply has different degrees and types of protection. Here are the most common ones.
- OCP (Over Current Protection): against power surges;
- OVP (Over Voltage Protection): against power surges;
- OPP (Over Power Protection): overload protection, sometimes called OLP;
- OTP (Over Temperature Protection): from overheating;
- UVP (Under Voltage Protection): from undervoltage;
- SCP (Short Circuit Protection): against short circuit;
In this case, the computer does not turn on due to the protection against power surges. It turns off the current flow through the power lines. This occurs by charging a special capacitor of the protection circuit, which, when charged, does not allow the system to turn on. In order for the system to turn on, all we need to do is pull out the power supply cable (220 V) from the power supply for 3-5 seconds and plug it back in (we will discharge the corresponding capacitor).
Thus, we “reset” the protection of the power supply and it can continue to work.
This is what they call a “classic of the genre” :) Now I would like to talk to you about more atypical cases when the computer does not turn on. In my practice, they met several times and I thought that this was quite enough to talk about this possibility.
So, let's start the "memory session" :) On one of the working office machines I installed USB mouse with this adapter for the PS/2 port:
Apparently this same adapter, over time, began to cause a local short circuit (short circuit) in the connector, which automatically triggered the corresponding power supply protection circuit. As a result, the computer did not turn on, it did not turn on at all. It is not clear who connected the mouse through the adapter and why, but after connecting the device directly to the USB connector, everything worked fine.
So - keep that in mind.
Another example: the management department calls - " The computer won't start". I come - it really doesn’t start. I try a couple of them, which I usually sort through on the spot. No result. I take the system unit to our IT department for a “debriefing” :) I only take the “box” itself (without cables, keyboard and mouse) I bring it to my place, connect the cables and input devices - everything works!
Using the trial method, it was revealed that the reason that the computer did not start was a non-working keyboard (more precisely, its microprocessor). The keyboard has been replaced. It happens that when the keyboard is not working, the internal system speaker emits three short beeps in a row. sound signals.
And here is another case from my practice. A security guard from our work brings his home PC and says: computer won't turn on, I don’t know what the reason is, please look. Why not help a good person, let's see!
I bring it into my office, take it out of the box, put it on the table and do an initial visual inspection. What should I tell you? I'd rather just show you a few photos:
What was the man doing with the car!? And this mysterious phrase of his: " won't turn on, don't know why?..." :)
What do I want to draw your attention to by giving these examples? Try to consider everything when diagnosing possible options. Think more broadly, do not focus only on some “standard” list of faults. If the computer does not turn on, first disconnect all its external peripherals and input devices, what if they are the reason? Well, if the computer is not yours, do you take into account the degree of technical adequacy and literacy of its owners? :)
I sincerely wish you good luck in this painstaking task!
No matter how modern and powerful computer If you didn’t buy it, over time all sorts of problems would start with it. One of these problems is when the computer does not turn on at all. I believe that this problem is unpleasant and I would like to teach you how to solve it. I am sure that if you have been using a computer for a long time, then you have had such a problem when you press the power button on the system unit, but nothing happens or the light comes on, the cooler starts to work but immediately turns off and the computer does not show any signs of life. It may be that when you turn on the computer, it starts beeping and nothing else happens.
Today you will find out what are the reasons for this malfunction and why the computer does not turn on. In general, we continue to expand our knowledge in computer repair.
Why won't my computer turn on?
The most in a simple way determine what is the cause of the problem described, listen to the sounds of the speaker. If the computer is not working, it will beep, that is, make sound signals, which for me personally are not very pleasant. If you hear such signals, then everything is not so bad and you can find out why the computer does not turn on. But if you don't hear any such sounds, don't be upset. Perhaps the tweeter itself is not connected to the motherboard.If the system unit has a special speaker or tweeter that came with the motherboard and remains in the box, it must be connected. You need to connect the speaker to the contacts on the motherboard. In order not to make a mistake and not to connect or disconnect unnecessary things, you need to read the instructions for the motherboard. You will definitely find the answer there.
The sounds your computer makes will depend on the BIOS manufacturer (Award, AMI, Phoenix Bios). If you do not know what BIOS you have, then the instructions for the motherboard will again help you. If you threw away the instructions, then all the information can be found on the Internet. Even if the computer does not work, everything is fine with the phone. Enter the name of your motherboard, which you can find out by examining the motherboard itself, and look for all the information you need.
But, let's return to our topic of BIOS signals. The most common of them:
- Award or Award - Phoenix BIOS
Long repeating signals - RAM not found or not working
- AMI Bios (American Megatrends, Inc)
2, 3 or 4 short beeps – RAM problem
5 short beeps – the processor may be faulty
1 long, 3 short beeps – video card malfunction
- Phoenix Bios
2 short beeps and 1 long beep – RAM fault.
These are the most common BIOS signals that you may have. In fact, there are many more of them. You can find out about them by reading on the Internet.
And so, we can conclude, based on the popularity of sound signals, that there are also the most popular reasons why a computer does not turn on. These sources of problems include:
- Problems with 220V power supply
- The power supply is faulty
- Battery ran out
- Lots of dust
- Problems with components or cables
- Bad power button
- Faulty motherboard.
- Now let's talk about each problem and its solution separately.
- Problems with 220V power supply.
It is also necessary to take into account the number of devices and devices that are connected via surge protectors or extension cords to one outlet. Perhaps you overloaded the outlet and the computer did not turn on due to the protection. To test this option, you need to disconnect all devices that are powered from one outlet and leave only the computer. Perhaps in this case it will work. If the network voltage is very high or low, the computer will also not turn on. Moreover, there is a high probability that it may burn out. You can check the voltage with a special device or using an incandescent light bulb by eye. The main thing is not to confuse the lamp with an energy-saving one.
If the voltage drops, then the light bulb will shine dimmer, but if it is higher than usual, it will burn brighter. Also, at high voltage, the light bulb can light up and immediately burn out. But this verification option is not particularly safe, so it is better to get a tester.
There are times when the outlet is fully operational, but the computer still does not receive electricity. This occurs due to poor contact of the power cable. Disconnect the cable from the power supply and reconnect it as tightly as possible.
It’s stupid to remind you, but still. It is worth remembering the buttons next to the connector on the power supply. It must be turned on. Sometimes it gets so funny that you’ve already tried everything, but the computer still won’t turn on. It turns out that the button on the power supply was turned off.
But don't press any other switches. There may be an input voltage switch on your power supply. It is usually red. You can't touch him at all!!! Its purpose is to switch the input voltage level between 127 and 220V. This is done in order to use the power supply in another country where the mains voltage is 127V, such as, for example, in the USA.
Problems with the power supply.
If you are convinced that everything is in order with the power supply, then you need to start checking the next element - the power supply. After all, it is where the power goes when you turn on the computer. In most cases it is faulty unit power supply causes a “dead” computer.
The fact is that in our country people are gradually getting used to saving on everything. And computer elements are no exception, especially if you look at how much they cost. People naturally prefer a Chinese cheap copy of the power supply.
But this position regarding the computer is generally unprofitable. Some users do not understand how important the power supply is in the computer system unit. And we are talking not only about the maximum permissible power, but also quality manufacturer. It’s very good if the power supply is covered with a copper basin without catching anything. In this case, you buy a new power supply, only one that is of higher quality and more reliable. And that’s it, the problem with starting the computer will be solved. But there are times when the power supply “dying” drags some elements with it system unit, or even the entire computer. And in this case you will have to buy new computer. Agree, it’s scary to even read about this! But I hope things aren't so bad for you.
To check the power supply, install a known-good element into your system unit and check whether it will work. If there is no such working power supply at hand, then we will check the performance of our part. But we can’t do without a voltage tester. Such a check can only be carried out when the lights come on when the computer is turned on.
The test using a tester is simple: take any power connector and measure the voltage: between any black and red wire there should be 5V, and between black and yellow 12V.
Some power supplies, when used for a long time, acquire the effect of “sticking” of the internal protection. Pull out the cable and leave it for about 10 minutes. After that, connect the cable back and start the computer. If the computer still does not start, then you need to proceed to checking the following elements.
The battery has run out.
Every motherboard has a small 3V lithium battery. It supports volatile CMOS memory that stores BIOS settings. On a computer that has been used for a long time or has simply been left idle for a long time, the battery will run out and all settings will be lost. A dead battery is easy to recognize. Each time you turn it on, the time will be lost. Sometimes an error occurs at startup and the BIOS asks you to enter it and resave the settings. But there are times when, due to this dead battery, the computer does not turn on at all or turns on only every other time. Again, if you have a voltage tester, you can easily check if the battery is working. If you don't have a tester, it's better to replace the battery. It is inexpensive and sold in any computer store.
The computer got dusty.
If there are already carpets of dust inside the system unit, then it is not surprising that the computer does not turn on. Do not forget that the system unit must be cleaned regularly and the thermal paste on the processor must be changed. It is best to clean with a vacuum cleaner and a brush.
Don't forget about the contacts of the RAM and boards. They also need to be cleaned. Just before this you need to completely disconnect the computer. Taking the RAM out of the slots, using a regular grater, also known as an eraser, we clean the contacts. We try, they should shine. But do it very carefully. Often there are microscopic parts located above the contacts. There is no way to touch them.
To clean the contacts of the memory slots from dust, you can use a toothbrush, shaving brush or any other brush, as long as they are of the appropriate size.
At the very end, we clean the fans and check their performance. If the fan does not work, the computer may turn off immediately after turning on. Large quantity Dust in the system unit will affect the overheating of the computer. Actually, because of this, the computer may not turn on, or it may constantly reboot.
The problem of components and cables.
If anyone has reached this stage of verification, then it is worth working by the method of elimination, because you never know in which particular part of the system unit the problem lies. The check should begin with those parts that are absolutely necessary to start the computer. All other elements must be disabled or completely removed from the system unit. In short, we leave the motherboard, the processor and fan connected to it, RAM, if there is no built-in video card, then we leave that too. It's also worth connecting a keyboard. If you only have one stick of RAM, then insert it into another slot. If the computer with these elements is working properly, then we begin to connect the remaining elements in turn. Next you need to connect the hard drive. By gradually connecting the elements you can find the problem area.
There is a high probability that the part of the system unit itself will be in good order, but the cable or cable may not work.
Problem with the power button.
One of the reasons why the computer does not want to work may be hidden in the start button of the system unit. Perhaps the button does not close the contacts well enough. It is clear that because of this the computer will not turn on. It is very easy to check its functionality. To do this, you need to inspect the motherboard and find the place where the wire from the front panel of the system unit case is connected. And there you can easily find the “Power” connector. Pull out the connector itself and use a screwdriver to close the two contacts. If the computer still does not turn on, go look for the problem further.
Problem with the motherboard.
If you did everything as described above and the computer does not start, then I have bad news for you - there is a problem with the motherboard. There is a high probability that you will have to replace it with a new one, but it is now oh so expensive. Yes, and you will want to change the motherboard to a newer one. Accordingly, you will have to change the processor, and then the RAM. In short, the entire system unit will undergo an upgrade. But, if you change a motherboard from the same series as yours, it must have:
- the same processor socket(socket)
- required number of RAM slots, of the same type (DDR, DDR2, DDR3...)
- connection interface available hard drive(IDE, SATA)
- a sufficient number of expansion slots for existing cards (PCI, PCE-Express)
You shouldn’t rule out repairing the motherboard, especially if it’s under warranty. But in this case, you will have to sit without a computer for a long time. From my own experience, I know that no one is in a hurry to repair the motherboard under warranty.
If there is no warranty, then you should send the motherboard for repair if the repair work does not exceed 30% of its price.
After you have independently checked the elements of the system unit and have not found a problem, there is no need to do anything yourself. You can only make it worse. You will have to call a specialist to your home so that he can “diagnose the patient.”
Actually, that's all. I’m sure our article helped you and you fixed your computer. Stay with us and learn a lot of new things.
Why the computer won't turn on - the first step towards finding out the reason
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 repeating signals - RAM not found or not working
AMI Bios (American Megatrends, Inc)
- 2, 3 or 4 short beeps – RAM problem
- 5 short beeps – the processor may be faulty
- 1 long, 3 short beeps – video card malfunction
Phoenix Bios
- 3 very short and 4 short beeps – the video card is faulty
- 2 short beeps and 1 long beep – RAM fault.
Let's identify the main reasons why the computer does not turn on, and we will follow the path of identifying the source of the problem:
- Problems with 220V power supply
- The power supply is faulty
- Battery ran out
- Lots of dust
- Power button
- Motherboard is faulty
Some may say that what is proposed below is superfluous, but personal experience says otherwise. If your laptop or computer does not turn on, check the cable connections (not only the plug plugged into the socket, but also the connector connected to the system unit), the functionality of the outlet itself, and other things related to the connecting cables (possibly the functionality of the cable itself).
It happens that everything is fine 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 you can find it on the back of the system unit). Check that it is in the “On” position (Important: do not confuse it with the 127-220 Volt switch, which is usually red and cannot be easily switched with your finger, see photo below).
If, shortly before the problem appeared, you cleaned the computer from dust or installed new equipment, and the computer does not turn on “at all,” i.e. there is no fan noise or power indicator light, check the connection of the power supply to the connectors on the motherboard, as well as the connection of the front panel connectors of the system unit.
The power supply is faulty
If you don’t have a known good power supply at hand, you can try checking the existing one. To do this you will need a voltage tester. You can measure the voltage only if the lights at least light up when you turn on the computer. To do this, take any power connector and measure the voltage: between any black and red wire 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 bother with its repair.
When some power supplies wear out, the internal protection may “stick” effect. Try unplugging the power cable and leaving the computer without power 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 at hand, let’s go through 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 the computer makes 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 humming, the coolers are working, the LEDs (“light bulbs”) on the system unit and keyboard (mouse) are glowing, then the problem is not in the PC, but the computer monitor simply does not turn on. In fact, most often this indicates problems with the computer's power supply, RAM or motherboard.
In the general case (for the average 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, turn off 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 is not the monitor or even the video card, but the main reasons: RAM and power supply.
Problems with components or cables
Here we need to work by exception. 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 initial launch 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 tightly inserted). We try to insert the RAM into another slot or leave only one stick (if there are more of them). If the computer turns on, then connect hard drive and see if it loads operating system. If yes, then we connect the devices one by one and thus find the culprit. By the way, the faulty device may still work, but the whole problem lies in the cable or cables. Therefore, they must also be taken into account. See also Troubleshooter and How to make your computer boot and shut down faster.
The battery is low
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. This is easy to notice if the time is reset every time you turn on the computer. Sometimes an error occurs at startup and the BIOS asks you to enter it and save the settings. But in some cases, the computer may not turn on at all or turn on only once. Checking the battery is not difficult if you have 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. If it does not close the contacts well, then it is logical to assume that the computer will not turn on. It's easy to remove a button. To do this, you need to find on the motherboard the place where the wires from the front panel of the case are connected, and find the “Power” connector there. The connector must be pulled out and the two contacts carefully closed with a screwdriver. If the computer still does not turn on, then move on. You will also find useful Tips for setting up and optimizing Windows and How to speed up your system by 50% without third-party programs.
Motherboard is faulty
The last option is 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’ll want to get a newer board, which means a new processor, and possibly RAM, and then the video card will catch up, followed by the power supply, in short, change the entire computer. Please note that if you change the motherboard to another of the same level, it must have:
- same processor socket (socket)
- required number of RAM slots, of the same type (DDR, DDR2, DDR3...)
- interface for connecting an existing hard drive (IDE, SATA)
- a sufficient number of expansion slots for existing cards (PCI, PCE-Express)
If the new motherboard has a different set of system logic, you may have to reinstall the operating system.
