This weird power supply issue took me a full day to figure out

I had a computer that would boot for about ten seconds, then shut off. No beeps, no post, nothing. I swapped the RAM, the CPU, even the motherboard, thinking it was a short. I must have spent six hours on that. The whole time, the power supply tested fine with my basic PSU tester. Turns out, it was a specific voltage rail on the PSU that would drop under load, but only after it warmed up a bit. My tester just showed a pass because it wasn't drawing enough power. I finally found it by swapping in a known good unit as a last resort. I felt like an idiot for not trying that first, but everyone always says to test the PSU first, right? Has anyone else run into a PSU that passes a basic test but fails under real load?

3 comments

3 Comments

angela_baker16d ago

Ugh, been there, those basic testers are basically useless.

sageross15d ago

Yeah, the "test the PSU first" advice is solid, but those basic testers really do just check if it's completely dead. @angela_baker calling them useless is a bit strong though, they have a place for a quick sanity check. The real problem is that a PSU can seem fine at idle but totally fall apart when the system actually asks for power, especially on one rail. That's why swapping in a known good unit is still the best test, even if it feels like you should have done it sooner.

xena3736d ago

Remember my buddy's PC that kept crashing in games? His cheap tester said the PSU was fine. He spent weeks messing with drivers and RAM. @sageross is totally right about the rails. He finally swapped the PSU with mine on a whim, and bam, problem gone. That tester gave him a false sense of security for a month.