Power supply won't power on the PC

Symptoms

• Pressing the power button does absolutely nothing, no lights or fan spin
• Power supply's own fan doesn't spin either
• PC worked fine before and nothing was intentionally changed
• No response even when trying a different outlet

Likely causes

• CommonPower supply switch turned off or set to the wrong voltageThe rear switch is easy to bump, especially during cleaning or moving.
• CommonFaulty or unplugged wall outlet or power stripTesting a different outlet or strip rules this out quickly.
• PossibleFront panel power switch cable disconnected from the motherboardThis is common after cleaning or working inside the case.
• PossiblePower supply itself has failedPSUs fail with age or from power surges, sometimes without warning.
• PossibleMotherboard short circuit preventing power-on as a safety measureThis is less common but can happen from a stray screw or bad component.

What to do

1. Confirm the power supply's rear switch is set to 'I' (on) and, on units with a voltage switch, set correctly for your region.
2. Try a different wall outlet, ideally testing with a lamp or another device first to confirm the outlet works.
3. Check that the front panel power switch cable is properly connected to the motherboard's designated pins.
4. If comfortable doing so, perform a 'paperclip test' on the power supply (with it disconnected from the motherboard) to see if its fan spins, which tests the PSU in isolation.
5. Check inside the case for any loose screws or debris that could be causing a short against the motherboard.
6. If the PSU fails the isolated test or everything else checks out, replace the power supply.

Tools and parts

• Paperclip (for PSU self-test)
• Multimeter (optional)

When to call a pro

If the power supply fails a self-test or the cause isn't obvious, have a technician verify it rather than risk a short or shock.

Safety