Why Your Computer Keeps Restarting and How to Fix It

A computer that restarts without warning is frustrating and can cause lost work. The cause is often one of a few common problems, and you can narrow it down with simple checks. Work through the steps in order, and save your work often while you investigate.

Check for overheating first

Overheating is a frequent cause of automatic restarts. Feel the vents and listen to the fans. If the computer is hot or the fans run loudly, clean the dust as described in how to clean dust out of a computer safely. Keep laptops on a hard surface, not a bed or sofa.

Check recent updates and drivers

A new driver or update can cause restarts. On Windows, check Settings, then Windows Update, then Update history. Remove the most recent update if the restarts began after it. On Mac, check whether a recent macOS or app update coincided with the problem.

Look at the event log

On Windows, search for Event Viewer and check the System log around the time of the restart. Critical errors and "Kernel-Power" messages can point to the cause. This takes some patience, but it gives real clues.

Test memory

Faulty memory can cause random restarts and blue screens. On Windows, search for Windows Memory Diagnostic and run it. Run one memory module at a time if you have several, and check the slots carefully.

Check the power supply

On a desktop, a failing power supply can cause restarts under load. If you recently added a graphics card, check that the power supply is strong enough.
On a laptop, try a different charger and power socket. A damaged cable can cause power interruptions.

Check storage health

A failing disk can cause crashes. Run the manufacturer's health tool, or use the built-in checks. Back up your files immediately if the drive shows warnings. See how to back up your computer.

Scan for malware

Some malware causes restarts or crashes. Run a full scan as described in what malware is and how to remove it.

When to get help

If the restarts continue after these checks, or if you see burning smells, sparks or swelling in a laptop battery, stop using the computer and contact a repair service. A swollen battery is a safety risk.

Frequently asked questions

Why does my computer restart only when I game?

Games stress the processor and graphics card, which can reveal overheating or a weak power supply. Check temperatures while playing.

Is a restart after an update normal?

Yes. Updates often need a restart to finish. Repeated restarts without an update reason are not normal.

Keep a note of when it happens

Write down the time of each restart and what you were doing just before. A restart during a game points to heat or the graphics card, while a restart when a USB device is plugged in points to power or a driver. This record helps a repair technician find the cause faster and saves you from guessing.

Check the power plan and sleep settings

Some restarts are caused by a power plan that is set to switch off devices aggressively. Review the advanced power settings, especially for USB and PCI Express power saving. On a laptop, make sure the battery is healthy, because an aging battery can shut the machine down suddenly even when it looks charged.