Windows computer randomly restarts? Here's how to fix it

Short of critical components dying or losing data, one of the worst things on a Windows PC is random restarts. At best they’re extremely inconvenient, and at worst you might lose all your progress on a critical task, forcing you to do the work over again. Below we’ll explore the potential causes of restarts and what you might do to fix them.

Why is my Windows PC randomly restarting?

On a micro level there are many potential reasons, but these can be sorted into several general macro causes:

• Power delivery issues. Either your PC isn’t getting enough power, say because of an insufficient PSU (power supply unit), or it’s getting too much because of a surge.
• Overheating. PCs are built to shut down or restart to prevent permanent heat damage. Normally this is only a risk with high-end gaming PCs, but it can also happen to less powerful machines with poor ventilation in hotter climates.
• Software glitches. While it’s rare for a bug to trigger a complete restart, it does happen. Historically Windows is infamous for this, in fact, although Microsoft has done a lot to tamp down the problem.
• Hardware defects. On a long enough timeline computer parts are bound to break, though hopefully not before you’ve upgraded to your next system.
• Malware. This is probably the least likely cause, but you could hypothetically be the target of hackers looking to hold you ransom or wreak havoc. Some people just want to watch the world burn.

How to fix a Windows PC that’s randomly restarting

The only way to solve restarts is to rule out the above issues one-by-one. Follow this checklist:

1. Check your power supply and connections. You could be dealing with trouble as simple as a loose cord or too much dust impeding electricity, but you could also be dealing with an insufficient adapter, wall outlet, or PSU. Make sure your PSU is rated to handle the wattage of all your PC components — NVIDIA’s RTX 4090 graphics card can pull as much as 450W by itself, never mind your CPU or cooling system. An upgrade may be necessary.
2. Watch for overheating, and improve cooling where possible. Use tools like Windows Task Manager to monitor  temperatures, and keep your computer both clean (inside and out) and well-ventilated. If things seem unexpectedly hot for any reason, you might point an external fan at your PC to help. If you have a tower case, consider upgrades like liquid cooling or more internal fans.
3. Install available software updates. By that we mean wherever possible on your computer, not just within Windows Update. If your machine has a video card from AMD or NVIDIA, for instance, use its native Windows app to update graphics drivers.
4. Run a malware scan. You can perform free malware scans via tools like Windows Security or Malwarebytes. While we’re at it, you should probably switch on Windows Security’s firewall and real-time protection options if they were previously off.
5. Uninstall any new apps or hardware if restarts began around the same time you installed them. This doesn’t make sense with a completely fresh PC, naturally.
6. Open up your PC and check for damage if you’ve tried all of the steps above without any luck. You’ll probably have to buy a replacement part if a repair is impossible or outside of your comfort zone, and in a worst-case scenario, it might be time for a new computer.
7. Reset or reinstall Windows. A reset is preferable, since it should keep some files and settings intact, but you might be forced to try the nuclear option if problems persist. Back up important files to the cloud or an external drive.

Reboot loops may not be your only computer problem. If your Windows computer isn’t turning on, there are steps to diagnose that particular issue too.