Turn off the PC and unplug the power cord
Press the power button for a few seconds to discharge residual power
Open the case and locate the PSU connectors
Check for visible damage, burnt smell, or loose cables
Use a PSU tester and connect the 24-pin ATX connector
Connect the 4/8-pin CPU power connector if the tester requires it
Turn on the PSU and read the tester results
Verify voltage readings are within acceptable ranges
Use a multimeter to test the 24-pin connector if no tester is available
Check the 3.3V, 5V, and 12V rails against standard values
Test the PSU under load with a known-good system or load tester
Monitor for voltage drops, instability, or shutdowns
Confirm the fan spins properly and the PSU stays stable during operation
Replace the PSU if readings are out of range or the unit fails to power on