Why does my computer turn off without warning?

Updated: 07/13/2023 by Computer Hope

If your computer turns off randomly, without warning, review the sections below for help with troubleshooting the problem.


This page is for computers that turn off and remain off.

If the computer restarts, see: Why does Windows restart without warning?

If the computer turns off immediately, see: Why does my computer power on and then immediately turns off?

If the computer doesn't turn on, see: Why won't my computer turn on?


Some steps below require you to work inside the computer. Before opening the computer case, be aware of the dangers of ESD (electrostatic discharge).

Heat-related issue

Power button

Most computers today are designed to turn off automatically if any of its inner components overheat. Often, heat-related issues occur when the computer is working hard, e.g., playing a graphically intense computer game or editing a video.

Start by verifying the fan on the power supply is working by examining the back of the computer. The fan should be moving quickly and smoothly. All other fans in the computer require you to open the computer case to inspect them. Once inside your computer, examine the processor (heat sink), video card, and case fans. If any abnormal noises have come from your computer (e.g., high squealing sound or low grinding sound), it could indicate a malfunctioning fan.


If your issues are on a laptop, we do not suggest opening the case. Instead, verify the fan on the side or bottom of the laptop is working and blowing out hot air. Also, with a laptop, you may want to invest in a cooler pad to help lower its running temperature.


Working on the interior of your machine provides an opportune time to clean the inside. Dust, dirt, hair, and other trapped debris can prevent proper air flow, leading to overheating.


Check the processor heat sink to make sure it is properly seated and has the correct amount of thermal compound.


If you do remove the processor heat sink, the existing thermal compound should be cleaned off the processor and heat sink, and new thermal compound should be applied.

If the power supply fan is not working correctly or at all, and the power supply is very hot to the touch, replace the power supply. An overheating power supply, due to a malfunctioning fan, can cause a computer to shut down unexpectedly. Continuing to use the faulty power supply can result in damage to the computer and should be replaced immediately.


If your BIOS monitors the RPM (revolutions per minute) of the fans, enter the BIOS and make sure the BIOS does not report any errors. Software utilities, such as SpeedFan, can also be used to help monitor fans in your computer.

Hardware-related issues


Before attempting to remove any hardware, rule out hardware conflicts by checking Device Manager for errors, see: How to Identify problems in the Windows Device Manager.

Any failing hardware component in your computer could cause your computer to unexpectedly turn off without warning. If you have recently added any new hardware, remove it from the computer to make sure it's not causing the problem.

If you have not recently installed any new hardware into the computer, the next best solution is to systematically remove non-essential hardware. For example, remove your modem, network card, sound card, and any other expansion cards that are unnecessary for your computer to operate. Running the computer without these cards may help diagnose your issue.

Problem with UPS or surge protector

Make sure any surge protector or UPS (uninterruptible power supply) is not causing your problem by connecting the computer directly to the power outlet on the wall. Also, if you have a UPS that connects a USB cable to the computer to manage power saving features, make sure it is disconnected.

If this resolves your problem, you may have a defective surge protector or UPS. With a UPS, there may be other issues, such as a UPS overload or UPS software reporting a power situation that require a shut down. Make sure there are not too many devices connected to your UPS and that it has the latest software updates.

Computer virus

Your computer may be infected with a virus or other malware designed to shut down your computer upon certain conditions. If your computer seems to be turning off when executing a certain program at specific times of the day, it could be infected.

If you believe your computer may be infected with a virus, download a free scanner. If you already have one installed, make sure your virus scanner definitions are up-to-date, then run a full scan.

Issue with the operating system

If, after following each of the above recommendations, your computer continues to shut off, you may be experiencing a problem at the operating system level. To see if this is the case, try the steps below.

  1. Reboot the computer and enter BIOS setup as the computer is booting.
  1. After you have loaded the computer in BIOS setup, let the computer sit.

If the computer does not turn off after staying idle in BIOS, your operating system installation may be corrupt. We recommend you either restore Windows to a previous date when the computer was not shutting off automatically or erase everything and reinstall Microsoft Windows.

Other failing hardware

If your computer turns off during (or after) installation of your operating system, other hardware is likely failing. Often, the hardware causing the issue is either the RAM (random-access memory), CPU (central processing unit), motherboard, power supply, or video card, in that order.

If you have extra parts or know someone with a similar configuration, you can swap each part to determine if it's at fault. Otherwise, you must have your computer serviced at a computer repair center.