Computer won't POST

[Rafterman223]

After having my computer previously work, one day when I turned it on, it didn't do a thing. I checked it out, and it won't even POST, but the motherboard power light is on. All of the fans turn on, but nothing happens. No monitor signal, and nothing happening. I tried to isolate the faulty component, and found out that the video card, hard drives, CD and DVD-ROMs, processor, and memory work. I basically isolated it down to the motherboard and power supply. The motherboard has not shorted out from dust or anything. I'm at a loss. Help if you can and thanks in advance.

[shunx]

Have you tried resetting CMOS?

Last time that happened to me I had to get a new board.

[weasel]

I've had this happen before and it turned out to be the power supply. One of the capacitors blew in the ps and lost the 3 or 5v line.

Jim

[Rafterman223]

resetting the CMOS did nothing. Could I check the 3V and 5V lines w/o a multimeter?

[JimmyG]

You will need a digital voltmeter. You can get one at Radioshack for a pretty low price.

You could also have a short from the mobo to the chassis. This can happen if you have a metal standoff screwed into one of the holes that has a signal line near the hole. Over time the insulation could migrate away from the signal line and short to the standoff.

One way to fix it is to take all of the standoffs out except one where it connects to a ground ring that circles the hole. Use insulated standoffs on all of the rest of the mounting holes.

[Rafterman223]

Thanks for the help, but it's not a short either. I tried plastic standoffs, and also tried to boot off of a cardboard sheet. I'm guessing it's a faulty motherboard, or PSU. Which one is more likely?

[JimmyG]

I think the Mobo is more likely. Your PSU should have a lot of headroom and it has way less complexity than the mobo.