computer problems... mobo or psu?

Hamju

Basically my in-laws' computer won't boot up after my father-in-law jiggled some sort of cable (I think USB cable for an external HD) and it shut down and won't turn on. Hitting the button does nothing, but when the case is opened you can see there's a light on the mobo, so it's getting some power. Is this most likely a mobo or psu problem? Is there some definitive way to test the psu to see if it's working (without the mobo) or test the mobo without the psu to see if it's fried? Thanks.

Tofystedeth

Hmmm, well, it's possible to short a USB port in such a way as the computer shuts itself down. This is a safety measure to prevent it from frying your mobo or starting a fire. So it's possible the computer shut itself down for such a reason and needs to be reset somehow, or it failed to shut itself down and for that reason doesn't work. Try unplugging it, and then holding in the power button for 5 seconds, then plugging it and trying to fire it up. Also, if you have it open, check the mobo for any popped capacitors and such.

edit: if you have a computer with a working PSU, you can always pull it and hook it up to this one, with minimal stuff hooked up, eg. CPU, RAM, Vid card. No drives. Also try removing everything but the CPU and 1 stick of RAM, and the video card (unless your mobo has built in) then see if you can get anything going that way.

Invisible

Did you make sure the PSU cable (the one that plugs into the outlet) is firmly attached to the PSU? The whole jiggling cables makes me think that could be an issue, because I've had that happen before.

Hamju

Oh, another thing, I have access to a multimeter, so I can test the PSU that way. I'll try bringing over a spare PSU and see if that'll help.