Computer turns on and then turns off

What to do if the computer starts up on its own

Sometimes the problem with the computer turning on by itself appears. Indeed, it looks unusual, because no one touches the computer, how it can turn on? Let’s look at some possible variants.

If there is a problem with the contact pins of the power button, it can actuate itself randomly. To exclude this option, you can open the lid of the system unit and disconnect the button from the motherboard. To do this, look on the motherboard where the front panel wires fit, find the jack with the word “Power” in it and disconnect it.

Also, some motherboards have a jumper that controls when the computer is powered on. For example if the jumper is jumpered, then at a supply of 220v the computer will turn on spontaneously. So, when power goes out and comes back in, this will happen regularly. You can find this jumper in the manual to your motherboard. It is usually called “Power-on after Fail”. On other boards, the behavior upon occurrence of power is set from the BIOS, about this below.

If the problem occurred after assembling or cleaning the computer or replacing the motherboard

If the problem with the computer shutting down right after powering on occurs on a newly assembled PC or after you have changed components and the POST screen is not displayed when you turn it on (t.е. The first thing to check is that you have connected the power to the CPU and that no BIOS logo or any other data appears on the screen.

The power from the power supply to the motherboard is usually supplied via two loops: one wide, the other narrow, 4-pin or 8-pin (may be labeled ATX_12V). And it is the latter that provides power to the processor.

Without its connection it is possible behavior when the computer shuts down immediately after powering on, and the monitor screen remains black. In the case of 8-pin connectors, two 4-pin connectors from the power supply can be connected to it (which are “assembled” into one 8-pin connector).

Another possibility is that the motherboard and chassis are short-circuited. It can occur for various reasons, but first make sure that the motherboard is attached to the case with mounting standoffs and they are attached exactly to the motherboard mounting holes (with metallized pins for earthing the motherboard).

computer, turns, then

If you have cleaned the computer from dust, changed the thermal paste or the cooler before the problem appeared and the monitor shows something at the first power on (another symptom. after the first power on the computer does not shut down longer than after), then with high probability you have done something wrong: it looks like a sharp overheating.

This could be caused by an air gap between the heatsink and the processor cover, a thick layer of thermal paste (and sometimes you see a situation where there is a factory polyethylene or paper sticker on the heatsink and it fits on the processor along with it).

Note: Some thermal greases conduct electricity and can short out the pins on the cpu if not applied correctly, this can also lead to startup problems. See. How to apply thermal paste.

Additional items to check (provided that they are applicable in your particular case):

  • Is the video card well seated (sometimes force is needed) and if additional power is connected to it (if needed).
  • Did you check the power on with a single memory stick in the first slot?? Is the RAM memory well seated.
  • Your surround processor has been installed correctly, and the processor feet are not bent?
  • Is the CPU cooler connected to power.
  • Is the front panel of the system unit properly connected?
  • Does your motherboard and BIOS revision support the installed CPU (if you changed CPU or motherboard).
  • If you have installed new SATA devices (disks, drives) check if the problem persists when you unplug them.

Why does the computer immediately shut down after startup??

No computer is immune to hardware problems. Many components deteriorate and become contaminated over time and this then has an impact on the performance of the computer as a whole. Some factors accelerate these processes, for example working through too hot conditions, not cleaning internal components for a long time, etc. д. However, even if the computer (PC) has been well taken care of, it is in any case not immune to the effects of time. After some time malfunctions will inevitably begin to occur, and you will have to fix them after that, spending some number of minutes and seconds. But in any case it can be recovered later.

The essence of the problem

Very often with technical problems with PC the same situation occurs. it starts to switch off by itself in a few seconds/minutes after it is started. In this article we will look at why this happens and tell you what to do in such cases, what problems are solved, how it is repaired afterwards in case of any trouble. sometimes the same few minutes are enough (seconds, however, are much less frequent).

The simplest causes of shutdown

There are a couple of the most common culprits for why the computer spontaneously turns on and immediately shuts down within a few minutes/seconds. So, why can it be with PCs:

  • Contamination of the system unit interior may be the cause of the shutdown. As trivial as it may sound, it is probably the most common root cause of most problems. If the computer is not cleaned for years, the dust will settle a huge layer on all its components: coolers, chips, boards, etc. д. So the first thing to do when you have trouble turning your computer on. it should then be well cleaned from the inside. It will take a bit longer than minutes and seconds, but it will dramatically increase performance. In general, preventive cleaning of the interior is recommended about once every six months.
  • Another reason for the computer to shut down may be the RAM. Its slots, the slots themselves to connect them may be out of order. Also, if the computer has been moved around or moved around in any way, the memory strip may have become loose. So the first thing to check whether they are well connected to the motherboard. If you haven’t noticed any abnormalities, you may insert the memory stick into a different slot, or if you have several memory sticks, remove one of them and try to turn the computer on without it. Perhaps the answer to the question of why there are troubles, lies in only one strip of RAM, without which the computer will run normally.
  • The computer can also shut down if the capacitors are swollen and therefore fail. Their physical deformation can be seen even by an inexperienced user, but to fix it himself will not be under force. If such a deformation has been detected, it is better not to do anything with your own hands. The best option here will be later delivery of the computer to the service center or the appropriate wizard, they will make the correction will not be difficult.

To reset the BIOS settings

In some cases restoring the default BIOS settings may help. For example, if you have accidentally changed the configuration of the computer (after which the start-up problems began), or it happened due to some other reasons. This can be done in several ways, the first of which is much easier than the second. But it will be realistic only if you can call the BIOS menu. Therefore, if your computer spontaneously shuts down not immediately, but a few minutes after powering on, then during the latter press the F2 or Del key (most often), which will turn on the BIOS. Then on the last tab “Exit” must be a line “Load Setup Defaults” (the name may vary slightly, depending on the model of BIOS). Click on it, confirm the application of the command and select the “Exit Save Changes”. Then wait to power on the computer to test. If the computer powers on and immediately shut down when started, not giving you the opportunity to enter the BIOS menu, then reset will have to do manually. It should be noted at once that for inexperienced users this method may be difficult, so if you’re not sure, it is better to ask one of your friends to do it or ask a professional.

So, you can do the zeroing manually through a special jumper on the motherboard. The last one is usually next to the CMOS battery. This battery looks just like an ordinary round battery, and CMOS. this is a special chip in the computer, which are the keys to start the PC and the data on the components in it. It is the CMOS memory that goes through the zeroing process when returning the BIOS to the default settings. The jumper is made in the form of 3 small plugs, the first two of which have a special “cap” on them. To return the factory BIOS settings, you need to remove this cap from the first two plugs and put it on the “second. third” for about 10. 15 seconds. After that put it back on the first two. Do it very carefully, so as not to damage the plugs, do not rush to do it in a few seconds, it is better to spend some minutes. Also next to the plug you will usually find “Clear”, “Clear CMOS”, “CLRTC”, etc. п.

If you have an expensive and high quality motherboard, most likely it has a special button with similar words which, when pressed, automatically resets your settings to defaults.

computer, turns, then

Individual component failures

Another reason why the computer shuts down after a few minutes/seconds could be the unstable operation of one of its components. The first thing under suspicion is the power supply. If it can’t stand the strain through itself, then after that constant computer shutdowns will be quite natural. that’s why trouble happens. You can ask friends or acquaintances to lend you their computer power supply and then turn on your own car with it. If it starts normally, it only confirms the guilt of the suspect, explaining why the computer has problems.

Overheating of the processor or graphics card is also a common cause of the computer shutting down. The shutdown in such cases occurs not in a few seconds, but in 5 to 10 minutes after switching on. You can check the temperature of your computer’s parts with AIDA64 program in the “Sensor” section. The normal temperature for a modern processor should not exceed 65 to 70 degrees (Why? Because this is a critical maximum). If your processor is hotter then your CPU is the problem. For video cards 65 degrees is quite normal, the evidence of overheating will be 90. 100 degrees and above.

Why the computer turns on by itself when it is plugged in?

A special function in the BIOS This is the main reason your computer turns on by itself right after you plug it in. It is turned on and off in the BIOS of the motherboard, namely. in the “Power Configuration” or “Power Management” section.

Verifying that the computer is turning on by itself due to a faulty power button is fairly easy.Unplug the power button and observe how the computer behaves when it is switched off. If it no longer turns on by itself, it is a sign that the button is defective.

Why does the computer shut down during the game?

Computer restarting or shutting down during gaming is most often caused by an overheated graphics card. It is usually solved by installing add-ons for both the game and the video card. But more often overheating is due to the fact that in the system unit a lot of dirt and dust, which in turn does not allow the cooling of components.

  • Unplug your PC.
  • Open the case and unplug the connector from the motherboard.
  • Make a U-shaped jumper out of a paper clip and short the green wire of the plug to the black one next to it.
  • Plug your PSU into a 220V power outlet.

Why does the computer shut down in 15 seconds??

After you turn your computer on, the screen at the very bottom will tell you that your computer will shut down in 15 seconds. The reason why the computer shut down is because of a shorted contact. Mainly USB pin. Check all the USB plugs, also check the USB connectors on the motherboard.

Disconnect unnecessary devices from the computer. You may have an extra power switch on the back of the system unit. check that too. If you have a laptop, put it on charge and wait at least 30 minutes before trying to power it up again.

What to Check if the Computer Turns On and Turns Off Right after Assembly or Upgrade

Processor power

If the motherboard logo does not even make it to the PC screen, make sure you have connected the power supply cable to the correct connector on the CPU. This is most often an 8-pin cable. Some units use two 4-pin plugs for this, but top gaming processors may use as many as two 8-pin plugs.

Read your motherboard and power supply manual if you are not sure what to connect. But in general the power plugs are designed in such a way that it’s hard to push them in the wrong way. only with force. The main thing is to make sure that the latch fits into the groove.

System cooling

Sometimes the cause of a computer shutting down is a cooling problem. Make sure you’ve properly applied thermal paste to the CPU’s heat spreading cover and connected power to the CPU cooler or water cooling system.

Remove the foil from the heatsink before pressing it to the CPU. This is something newbies often forget. Or maybe it’s a conditioned reflex from the days when a TV remote control was left in its wrapper.

The film must be removed from the heat sink’s heat dissipating surface before installing it. Picture: Scythe

Spread a thin layer of thermal paste. Once the heatsink is pressed it must not spread around the processor, otherwise a short circuit is possible.

Power supply

Sometimes first-time homebuilders connect overly voracious gaming components to an underpowered power supply. Check if your device has enough power. This can be done with special calculators. If the power supply doesn’t hold your hardware, replace it with a suitable one.

Mounting the motherboard

The motherboard is attached to the standoffs and must not come into contact with the backing plate. Image: Petteri Aimonen / Wikimedia Commons

Another possible cause of the problem is a short circuit between the motherboard and the case. It is supposed to be attached to the base plate with thin, screw-in standoffs supplied with the case, but some people manage to bolt it right to the metal. In the end, the board short circuits, and it’s not certain that it can be repaired in a service center.

Before applying power, check where on the board the holes for the standoffs are located. Place the standoffs on the support plate in the right places and attach the board to them, not to the plate itself.


Remove all the flash cards, then put one of them in the first slot. Press the front panel gently to make sure it is seated properly. Try starting your PC. If it turns on normally, the problem is in one of the plugs. Try them all this way, find the bad one and replace it.

Contacts connected to the motherboard

Make sure the motherboard power connector is larger, and the CPU power connector is smaller. Image: Tobias Maier / Wikimedia Commons

Make sure that the motherboard is receiving power normally, and that the main power cable is connected normally. It is not difficult to guess which cable from the power supply is connected to which one: their plugs have different sizes.

Make sure the graphics card is securely seated in the connector and extra power is supplied to the graphics card.

The place for additional power supply on your graphics card. Image: NVIDIA.

Check to see if you connected the front panel of the system unit properly. If you can not figure out the plugs, look in the manual to the motherboard.

Front panel contacts. power and reset buttons. Image: Slamet Setiawan / Pxhere

Maybe the power button wires are just not connected correctly, that’s why the PC “doesn’t start”.

New hardware and devices

A motherboard with a graphics card, SSD, and RAM connected. Picture: Rainier Ridao / Unsplash

If the problem occurs after upgrading your PC, remove all extra memory, new graphics cards, sound cards, Wi-Fi modules, hard drives and drives other than the boot drive, fans, and other peripherals. Ideally connect the monitor directly to the video output of the motherboard if your CPU has a video core.

Then plug in the hardware one by one. When you get to the defective one, the PC will stop turning on. You’ll have to replace the component with a working one.

Be sure to read the instructions when connecting components, especially small plugs from fans or the front of the computer. Improper connection leads to polarity reversal and short circuit.

Revision of the motherboard firmware

If all hardware fails, but the computer stubbornly refuses to boot, check if the revision of the motherboard firmware is suitable for your processor. You can check it on the motherboard manufacturer’s web-site.

To make the motherboard work properly with the processor sometimes you need to update the BIOS. If you are not confident in your abilities. take the board to a service center. If you want to do it yourself. borrow a suitable processor for the time of the upgrade, flash and install yours back.

No culprit, no suspects

Often the crashes like ours occur spontaneously. without any apparent reason and against the background of the normal computer operation. The user does not suspect that any specific device is faulty. To be more precise, the whole hardware is under suspicion. What to do in such a situation?

Let’s start with a simple. Unplug the PC without opening the case or press the power key on the power supply.

Next press the power button on the system unit and hold it for 20-30 seconds. After that connect power and try to start the PC as usual. If the problem is caused by a build up of static electricity or residual charge in the capacitors, the next startup will be normal and the problem will not affect the further operation of the computer.

If that does not work, reset the BIOS to the default settings. There is a separate article on this subject, so we won’t go into details on how to do it. To reset, use the Clear_CMOS jumper, or a round battery tab usually near the jumper.

Perform the following actions one by one, going to the next if the previous one did not help. After each reset attempt to power up the PC.

  • Unplug all peripheral equipment from the computer, leaving only the keyboard and monitor.
  • Visually inspect all internal devices and communications of the system unit, without disconnecting anything yet. Verify that all connections are secure and tight.
  • Observe the CPU cooler and case fans behavior when pressing the power button. Jerking and stopping, as mentioned above, is a typical symptom of a short circuit. Cyclic spinning and stopping most often indicates a BIOS crash. No rotation at all. problem with 12v power supply, fan breakage or glitch in fan control.

If BIOS failure is likely the cause of the problem you can try to repair it. Many modern motherboards allow you to do this without a programmer.

If a short circuit is the likely cause:

  • Disconnect all non-essential equipment from the motherboard to turn on the computer. Leave the CPU, cooling system, memory (one module is enough), video, keyboard and power supply connected. If the problem has not gone away, the culprit is among the remaining devices.
  • Check that the power supply fires when disconnected from the motherboard. If a short circuit occurs in the load (the powered equipment), switching power supplies will shut down. This is how they protect themselves from overloading, which is caused by excessive current consumption.
  • After you find out that the power supply is intact, remove all the remaining hardware from the PC case. This should be done for two reasons: to eliminate the shorting of the motherboard to the case (occurs if the system is not assembled correctly) and to inspect the devices from all sides in good light.
  • Inspect the equipment for defects as described above. If there are obvious signs of failure, replace the problem device with a compatible counterpart.
  • Put together a stand of devices on the table, connect the power supply and check for hot elements on the motherboard and video card. If there is. you have found the problem node. If not, start the test bench by shorting the power switch on the motherboard. Where exactly they are located on your model, you can find in the description to it.

Further search for the fault of the computer, which turns on and immediately shuts down, it remains to continue with the replacement of the remaining hardware, in particular, memory and video cards. Although, if you have reached this stage, the most likely culprit is the motherboard. You can, of course, not stop here and move on to the diagnostics of this particular device, but we agreed to do it with our bare hands. Your direct hands and knowledge are your best helpers in solving any problems with your PC. The rest is secondary.