I already wrote a post about possible solutions for laptops shutting down unexpectedly, but this one is specifically for desktop computers.

If your PC turns off shortly after it boots up and it doesn’t let you do any work, you might want to try some of these possible solutions:

1. Boot into Safe Mode with Networking and scan your hard drive for viruses and spyware. It is quite possible that some spyware is responsible for this malfunction. If you don’t have a good scanning program, download Malwarebytes and SuperAntiSpyware. Malwarebytes lets you do a quick scan.

2. Open up your case and see if the CPU fan is working and if the heatsink sits correctly. You might also want to check if there is enough thermal compound between the heatsink and the CPU (check your CPU manual to confirm that your model needs thermal compound). Thermal compund looks like cream and is used to cool down the CPU.

3. Maybe the power supply is faulty. Use a spare one to test this.

4. Check your memory (RAM) with a free program memtest and exchange it if you have spare module(s).

5. Clean the PC case if there is lots of dust in the fan and power supply.

6. Inspect your motherboard – maybe there is a faulty chip or capacitor.

7. Power cords rarely fail, but it may be another option. Test your PC with another cord.

8. Check the power options in Control Panel/Power Options. It should be set to Always on.

9. Check to see if Automatic restart/shutdown on system failure is turned on. Right click on My Computer, then Properties, Advanced and under Startup and Recovery, click on Settings. Next, under System Failure, untick “Automatically restart”.

10. Go into your PC’s BIOS (press DEL or F2 at startup) and see if the overheating function is enabled (set to shut down if CPU reaches certain temperature).

One of my friends recently had this problem and he only resolved it by using 3 different malware scanning programs: Malwarebytes, Super AntiSpyware and Spybot Search & Destroy.