Windows won’t start

Computer keeps restarting itself before reaching the desktop

The PC powers on, shows the Windows logo or BIOS screen briefly, then restarts on its own, repeating the cycle endlessly. This points to either a startup failure that triggers an automatic restart or a hardware instability issue.

Difficulty
Intermediate
Time
30–90 minutes
DIY cost
$0–$30
Pro cost
$100–$220

Symptoms

  • PC restarts every 5–30 seconds without ever reaching login
  • May briefly show BIOS logo, Windows logo, or a blue screen flash
  • Fans spin up each time it restarts
  • No error message stays visible long enough to read

Likely causes

  • CommonWindows set to auto-restart on system failureBy default Windows restarts instantly after a crash, hiding the actual error.
  • CommonCorrupted system files or failed updateDamaged startup files can crash Windows immediately after loading.
  • PossibleOverheating CPU shutting the system downThermal protection can restart the PC repeatedly if cooling has failed.
  • PossibleFailing power supplyAn unstable PSU can cause resets during the high-power startup phase.
  • PossibleFaulty RAMBad memory often causes crashes very early in the boot process.

What to do

  1. Interrupt the restart cycle 2–3 times by holding the power button as soon as the logo appears, which forces Windows into the recovery environment.
  2. In Advanced options, go to Startup Settings and disable 'automatically restart on system failure' equivalent by choosing to see error details, or check the actual blue screen error if one flashes.
  3. Check whether the PC feels hot to the touch or fans are running at full speed; overheating can cause repeated shutdowns.
  4. For desktops, open the case (unplugged) and check that CPU fan and case fans spin freely and aren't clogged with dust.
  5. Run Startup Repair and 'chkdsk C: /f' from the recovery environment's Command Prompt.
  6. If you have two or more RAM sticks, remove all but one and test booting, then swap which stick is installed to isolate a bad module.
  7. If overheating or hardware failure is suspected, have the PC's cooling and power supply inspected by a professional.

Tools and parts

  • Bootable Windows recovery USB drive
  • Compressed air for dust (desktops)

When to call a pro

If the PC feels hot, smells burnt, or restarts even in the BIOS screen before Windows loads, stop use and have a technician check the power supply, cooling, and motherboard.

Safety

Generally low risk

Generally low risk for a careful person. Stop if anything looks different from what this guide describes.

Related guides

Operator provides AI-generated troubleshooting information. It can be wrong. For safety-critical, electrical, gas, structural, medical, automotive safety, or other high-risk problems, consult a qualified professional.