Your PC powers on, runs for a few seconds, shuts off, and starts again, over and over, never reaching BIOS or Windows. A boot loop is frustrating but usually has a short list of causes: an unstable memory profile, a power fault, or a Windows startup problem. Work them in order and most loops resolve without replacing anything.
Two kinds of boot loop
Distinguish where the loop happens. If it restarts before any logo, the problem is hardware or firmware: RAM, power, or BIOS. If it reaches the Windows logo or spinner and then restarts, the problem is software: a bad driver, update, or corrupted OS. That split points you at the right fix fast.
Hardware loop, before BIOS
The most common trigger on a new build or after enabling an overclock is an unstable XMP or EXPO memory profile. Clear CMOS to reset BIOS to defaults, which disables the profile, and see if the loop stops.
| Where it loops | Likely cause | First fix |
|---|---|---|
| Before any logo | Unstable RAM profile | Clear CMOS, disable XMP/EXPO |
| Before any logo | Power delivery fault | Reseat EPS and 24-pin, test PSU |
| Before any logo | Bad RAM seating | Reseat or test one stick |
| At Windows logo | Driver/update failure | Boot Safe Mode, roll back |
| At Windows logo | Corrupted OS files | Startup Repair from install USB |
The fix sequence
Reset the firmware first
Clearing CMOS, via the jumper, the button, or pulling the battery for a minute, returns BIOS to safe defaults and undoes a bad memory or overclock setting. This alone cures a large share of pre-logo loops on new builds. Reboot, and only re-enable XMP or EXPO once the system is stable.
Then power and memory
If it still loops, reseat the EPS 8-pin and 24-pin cables and the RAM, testing with a single stick in the correct slot. A weak or failing PSU can also loop by tripping protection at boot, so a known-good supply is a useful test.
Software loops
If the loop starts at the Windows logo, interrupt boot a few times to reach recovery, then use Safe Mode to roll back a recent driver or update, or run Startup Repair from a Windows install USB. A recent GPU driver or update is a frequent culprit.
Preventing the loop from coming back
Fixing a boot loop is satisfying, but the goal is a system that stays stable. A few follow-up steps make sure the same loop does not return the next time you tweak a setting or install an update.
Re-enable overclocks one at a time
After clearing CMOS resolves a pre-logo loop, resist turning every setting back on at once. Re-enable the memory profile first and confirm a stable boot, then adjust anything else separately. If the loop returns the moment you re-enable a specific setting, you have found the exact culprit rather than guessing among several changes.
Keep recovery media ready
For software loops, a Windows install USB is your safety net. Create one before you need it, so a future update or driver problem that triggers a loop can be met with Startup Repair or a rollback immediately. Being able to reach recovery in minutes turns a frightening loop into a routine fix.
Log what changed
Most boot loops follow a change: a new memory profile, a BIOS update, a driver, or a Windows update. Noting what you altered just before a loop began points straight at the cause and speeds the fix. Stable systems rarely loop on their own, so the trigger is almost always a recent, identifiable change.
FAQ
Will clearing CMOS delete my files?
No. Clearing CMOS resets only BIOS settings like the memory profile, boot order, and fan curves, not your drives. You may need to re-enable XMP or EXPO and reset the boot device afterward, but your Windows install and data are untouched.
My new build loops the moment I enabled XMP. Coincidence?
Almost certainly not. An unstable memory profile is the number one cause of pre-logo loops on fresh builds. Clear CMOS, leave the memory at default, confirm stability, then try a lower profile or speed. Running slightly under the rated speed but stable is the fix.
Bottom line
Identify where the loop happens. Before the logo, clear CMOS to kill a bad memory profile, then reseat power and RAM. At the Windows logo, use Safe Mode or Startup Repair. Boot loops look catastrophic but usually trace to a setting, a cable, or a driver, not dead hardware.
