system won't start, PSU good

[JimS]

My system shut down normally last night, now it won't start. The standby power LED is on, but pushing the power button does nothing. I tested the power supply with a multimeter and all voltages are good on the main power cable and the 12V cable, I didn't test the drive cables because I assumed that they wouldn't cause the problem even if faulty. So, is it a safe assumption that my motherboard is bad, or is it possible that some other component could be shorting out the motherboard hard enough to cause it to appear bad? If it matters, the mobo is an Intel D975XBX, original revision, with a Core 2 Duo, I believe E6600. It's 5 years old, maybe 6, I don't remember. And I don't see any blown capacitors.

 

[Zaap]

...blown capacitors...

My immediate first guess. Did you check the graphics card as well for them? I've seen exactly the same situation you describe I can't even count how many times, with blown capacitors on the graphics card. Once replaced, the system boots right up.

 

[JimS]

Nope, I didn't check the graphics card for them, as it's almost new. I tried removing the card though, and nothing changes.

I did do something else though. For some reason, I got the crazy idea to permanently ground the PS_ON line on the power connector with a paperclip stuck in the back of the connector, on the theory that the worst that could happen is I need a new motherboard, which I figured I would anyway, and the best that could happen is maybe it just wasn't getting the signal for some reason and I'd get some error beeps or something if I could force it on. Well, it now boots and runs fine! The only problem is that whenever the standby power switch is on, the fans and drives run, so I have to shut it off by hand after I shut down Windows. But that's no more annoying than in the pre-ATX days, so unless something smokes, I might just leave it like that.