My Computer Shuts Off Randomly. What can I do?

A TechJunkie reader contacted us yesterday asking why their desktop computer was randomly shutting down. While difficult to troubleshoot specifically over the internet, there are a few key things to check. In case your computer shuts off randomly, here is what you do.

There are four main reasons why a computer may randomly shut down. They are:

• Heat
• Power
• Faulty hardware
• Software or operating system issue

To effectively troubleshoot random shutdowns, you need to look at each one of these main causes. The most common causes are heat and power. If a computer gets too hot, the BIOS or CPU will shut down to save overheating. If your power supply is not working properly, it will not supply the correct or stable voltage required. Again, the BIOS or CPU will shut down.

Faulty hardware and software are less common but do come up from time to time. If your computer shuts down completely, this is more likely hardware. If your computer reboots, it could be software. As the question was about shutting down and not rebooting, I will address only that.

As mentioned, it is impossible to offer specifics in an online tutorial. Instead, I will show you where you should be looking to isolate the cause.

Heat

Heat is the enemy of electronics and will cause your computer to shut down to save overheating and damaging hardware. Download and install HWMonitor or an alternative that shows voltage and temperature. Keep it running where you can see it and monitor your system temperature as you use your computer.

For safe operating temperatures for processors, check out this page. It is very helpful and shows a wide range of CPU types. Check this page for safe temps for Nvidia GPU. I cannot find an AMD equivalent page but assume the same max temp of 100C. This is the maximum tolerable temperature, not what your GPU should be running at when using games or intensive programs.

If you overclock, switching back to stock clocks is the first thing you should do.

If your computer is running hot, turn it off and remove all dust from the interior of the case. Make sure all case fans are working and are pulling air in from the front and pushing it out at the top or rear. Consider adding more fans or tidying cables for better airflow if temperature is an issue.

Power

Computers are very sensitive to power fluctuations. Even a slight variation in voltage can cause a motherboard or processor to shut down to protect itself. There are a few things you can check to verify stable power.

1. Use HWMonitor to check voltages do not fluctuate too much.
2. Use a UPS or power strip that manages voltage and provides surge protection.
3. Try using another power supply if yours is old.

It is useful to have a spare power supply around anyway if you depend on your computer. Buy a good quality one from a recognized brand and not a cheap import. You really do get what you pay for and this is one of those times where spending a little more on quality will repay you in kind.

If you don’t have a spare power supply, see if you can borrow one for a couple of hours to test. There really is no other way to troubleshoot power without one.

I always suggest using a surge protecting power strip for a computer. It not only protects it against those surges but also cleans up voltage from the mains. Even in the newest cities, mains voltage fluctuates quite a lot. Usually a computer power supply can cope, but refining that voltage using a power strip lower the stress on that power supply.

Faulty hardware

Faulty hardware is notoriously difficult to troubleshoot but is rarely the cause of random shutdowns. Unless something is obviously smoking, has melted or burned or is otherwise damaged, it is a process of elimination to find the culprit.

1. Return your BIOS to defaults and return to stock clocks if you overclock.
2. Remove one PCI card or RAM stick at a time and monitor. Replace and try another if the computer shuts off.
3. If you use external audio and/or graphics and you have onboard, temporarily switch to onboard audio or graphics and retest. This setting is in the BIOS. Remove the graphics or audio card before switching on again.
4. Switch RAM slots and sticks and monitor. Do each separately for thoroughness.

If your computer stops shutting off randomly, look at the last change you made. Make a note of what hardware was where and undo that final change. It is likely that your computer will shut off again. Perform that last swap again to make sure it wasn’t a one-off. If the computer remains stable, whatever you moved or removed is what is causing the instability. Replace it as necessary.

Software or operating system issue

It is rare that software or your OS would cause your computer to shut down randomly. Usually, a software glitch would trigger a reboot rather than a shut down. However, if you use Windows, all bets are off.

Perform all the steps above for heat, power and hardware. If it seems to be none of those and you use Windows, reboot into safe mode. Play a movie or run a simple browser game to get it working and monitor. If the computer shuts down, the issue is in Windows core. If the computer remains stable it could be something else.

1. Upgrade Windows and perform manual updates on all major drivers.
2. Check your BIOS version and update if necessary.
3. Temporarily remove any monitoring software or fan management software you may be using.
4. Check Event Viewer to any major warnings or shutdown messages and take appropriate action.
5. Uninstall any recently installed software or apps.
6. Perform a system restore if all else fails.

As you can see, there are a lot of factors in troubleshooting a computer that shuts off randomly. I find the causes are heat, power, hardware and software in that order, which is why I troubleshoot them in that order. It takes time and patience and you will be there a while isolating the cause.

Know of any other troubleshooting tips for random shutdowns? Tell us about them below if you do!