• Welcome to Overclockers Forums! Join us to reply in threads, receive reduced ads, and to customize your site experience!

If the voltages on my PSU are okay, does that mean my PSU is fine?

Overclockers is supported by our readers. When you click a link to make a purchase, we may earn a commission. Learn More.


Aug 25, 2004
My computer stopped starting up a little while ago. No beeps, POST, nothing. The fans and drives all spin up. I pulled everything off the board except for the CPU and nothing changed.

Anyway I grabbed a multimeter and tested the voltages on the rails from the 20-pin connector. I did this while trying to start up the computer, and they all checked out fine. I'm not 100% sure what I did was comprehensive. I just checked every red, orange and yellow wire off the 20-pin.

Since my voltages are fine, is this enough to say that my PSU is probably not the culprit?
If the voltages are correct (yellow = 12v, red = 5v, orange = 3.3v), the PSU is almost certainly not the issue with the no-start.
I would make sure that the CPU power connector is still plugged in correctly.
Thanks. I thought I was doing it correctly.

I've reconnected the power supply (including the CPU power connector) multiple times to the motherboard with the exact same result.

Previously I've had issues with the motherboard where it would only periodically detect my SATA drives ... and then it stopped detecting them entirely. Also, awhile ago I had an issue where I would have to try multiple times to turn the computer on before it would finally POST.

This sounds to me like it's got to be a CPU or motherboard issue, and I'm leaning towards motherboard.
I'd go for motherboard.
Have you reseated the CPU? That might be worthwhile.
Yup, tried that too. I'm gonna clear CMOS overnight and see if that makes a difference. I'm not optimistic at this point. This hardware is old anyway. Now I can justify an upgrade.
You'll need an oscilloscope to reliably check for bad caps. (A visual check usually finds them but not always.) A used one (nothing fancy, 5MHz is good enough for this, but I recommend at least 50MHz) can be quite cheap but probably still more than you want to spend.