Troubleshooting a Computer That Powers On Then Shuts Off

Is your computer turning off on its own right away or before the operating system loads? If so, you might be dealing with anything from an electrical short to a significant hardware issue.

How to Fix a Computer That Won't Stay On

This process could take anywhere from minutes to hours, depending on the cause of the computer turning off shortly after being powered on.

1. Troubleshoot the cause of the beep code, assuming you're lucky enough to hear one. A beep code will give you an excellent idea of exactly where to look for the cause of your computer turning off.

   If that doesn't resolve the problem, you can always return here and continue troubleshooting using the more general information below.
   

2. Verify that the power supply voltage switch is set correctly. If the input voltage for the power supply doesn't match the correct setting for your country, your computer might not stay powered on.

   Likely, your computer wouldn't power on at all if this switch is incorrect, but a wrong power supply voltage can also cause your computer to turn off by itself.
   

3. Make sure you're keeping the computer cool enough, or it might overheat to the point that it shuts down. Follow that link for easy tips anyone can follow to cool down their computer.
   

   Some computer cooling techniques for desktops require you to open your computer, but that's pretty easy to do.

4. Check for causes of electrical shorts inside your computer. It's often the cause of the problem when the computer powers on for a second or two but then powers off completely.

   Check inside your computer for issues that could cause shorting. Skipping this step could result in overlooking a simple electrical short and lead to unnecessary, expensive hardware replacements.
   

5. Test your power supply. Just because your computer powers on briefly doesn't mean the power supply unit is functioning properly. The power supply often causes more problems than other hardware and is frequently the reason a computer shuts down by itself.
   

   Replace your power supply if it fails any of your tests.

   If you replace the PSU, leave the computer plugged in for at least five minutes before trying to power it on. This pause allows the CMOS battery to charge a bit.

6. Test the power button on the front of your computer's case. If it's shorting out or merely sticking to the case, it might be why your computer shuts down by itself.
   

   Replace the power button if it fails your testing or if you suspect it's not working correctly.

7. Reseat everything inside your computer. Reseating will reestablish all the connections inside your computer, which may have wiggled loose over time.

   Address the following and then see if your computer stays on:

   • Reseat all internal data and power cables
   • Reseat the memory modules
   • Reseat any expansion cards

   Unplug and reattach your keyboard and mouse, too. It's unlikely that either causes this problem, but it's best not to overlook them while reseating everything else.
   

8. Reseat the CPU only if you suspect it might have come loose or wasn't installed correctly.

   We call this out separately only because the chance of a CPU coming loose is very slim and because installing one is a sensitive task. It isn't a big concern if you're careful, so don't worry!

9. Clear CMOS to erase the BIOS memory and return its settings to their factory default levels. A BIOS misconfiguration could be why your PC won't start up normally.

   If reseating the battery doesn't fix the problem, consider replacing the CMOS battery.

10. Start your PC with essential hardware only. The goal here is to remove as much hardware as possible while still keeping your computer capable of powering on.
    

    If your computer turns on, and stays on, with essential hardware only, proceed to Step 11.

    If your computer continues to turn off by itself, proceed to Step 12.

    This troubleshooting step is easy enough for anyone to complete, takes no special tools, and could give a lot of precious information. It isn't a step to skip if your computer is still shutting off by itself after following the steps above.

11. Reinstall each piece of non-essential hardware, one component at a time, testing your computer after each installation.

    Since your PC powered on with only the essential hardware installed, those components are working correctly. It means that one of the devices you removed is causing your computer to turn off by itself. Install each device back into your computer and test after each installation; you'll eventually identify the faulty hardware.
    

    Replace the faulty hardware once you've identified it.

12. Test your PC using a Power On Self Test card. If your computer continues to power off by itself with nothing but essential PC hardware installed, a POST card will help identify which piece of remaining hardware is to blame.

    If you don't already own and are unwilling to purchase a POST card, skip to Step 14.

13. Replace each piece of essential hardware in your computer with a "known good" identical or equivalent spare piece of hardware, one component at a time, to determine which part of the hardware is causing your computer to shut off automatically. Then test after each hardware replacement to determine which device is faulty.

    Most average computer users don't have a collection of working spare computer parts at their disposal. Our advice is to revisit Step 12. A POST card is not expensive and is a much more reasonable approach than stocking spare computer parts.

14. Finally, if all else fails, you'll likely need to seek professional help from a computer repair service or your computer manufacturer's technical support.

    If you're without a POST card and spare parts to swap in and out, you're left not knowing which piece of your essential computer hardware is faulty. In these cases, you have little option but to rely on individuals or companies with these resources.

Why Does My Computer Turn Off?

Because there are several reasons that your PC might be shutting off by itself during the boot process, you must step through a logical troubleshooting process like the one we've described above. Here are some possible causes:

• A damaged electrical cable.
• Incompatible hardware or drivers.
• Loose components inside the PC's case.
• A faulty power supply.