Possible Power Supply Issue

[AMDZen]

So I come home last night and one of my roommates says to me "My computer just shut off, for no reason, out of nowhere". I take a look, pull all the power, plug it in, still won't boot, it simply tries to start uo and doesnt.

Then I open it up, pull the 20-pin cable from the MoBo and plug it back in (after unplugging the PSU of course) and then swith the PSU back on and bam. The computer posts and procedes to boot up, like nothing is wrong.

It goes to windows, asks for login and suddenly dies again. All the power goes off, everything dies.

I am almost 90% that this is the PSU. But I want the input of some of you guys as well. We tried some other things, and once again I could get it to boot - this time for a little longer - I was able to open up am .mp3 and start playing it. Then the comp died again.

Please provide your opinion, just so I'm not missing anything. I have told my roommate to go get one at the local microCenter. The only decent brand they have is Antec, so he was going to get the TrueBlue 480watt. This way he could return it if it wasn't the PSU, no problems vs. the Newegg route which would present problems.

But then I got to thinking, I don't see how it could be anything else but the PSU. So maybe he can order from Newegg a new Fortron, PC P&C or the OCZ modstream which he likes. I just don't want him to order it and find out that its the motherboard instead. Let me know

 

[ribbon13]

Probably the PSU
I'd reccomend this one

 

[Sqube]

Like ribbon said, it's probably the PSU.

Just for future reference though, giving the specs of a machine, particularly when you'd like other people to help diagnose the problem, never hurts.

 

[imported_Kensai]

Measure the voltages coming from your PSU if they're out of spec, I'd suggest getting a nee PSU if you want your rig to work.
Though I've had experiences like that where I thought it was the PSU, but it ended up to be the mobo.

 

[Matthias99]

But then I got to thinking, I don't see how it could be anything else but the PSU.

From your description, it could also be a heat issue -- check that the CPU's HSF is still solidly mounted (and not coated in dust) and that the fan is working, and that your case/PSU fans are spinning. If your system is overheating, the CPU could overheat and crash, or the PSU could overheat and turn itself off to prevent it from burning out.

 

[AMDZen]

Thanks for all the reply's guys. I doubt its the CPU overheating, but will definetely check that. If it was that, I think the computer would still die, but not everything would power down (ie fans, fan speed controller, so on)

And for the description. Its a home made computer. Abit NF7-s MoBo, Athlon XP, 9600 VidCard, so on and so forth. the PSU is a ThermalTake, not sure how good they are.

The other thing, how would I check voltages if I can't get it to boot? Bios I assume, but not sure what the voltages should be, but I guess those would be on the PSU right?

 

[Matthias99]

Thanks for all the reply's guys. I doubt its the CPU overheating, but will definetely check that. If it was that, I think the computer would still die, but not everything would power down (ie fans, fan speed controller, so on)

If the CPU overheats, it *probably* wouldn't power off (it would just crash), but if the MB or PSU are overheating, it could shut down the whole system. I think it's most likely a flaky PSU, but it's worth checking into the temperatures as well.

The other thing, how would I check voltages if I can't get it to boot? Bios I assume, but not sure what the voltages should be, but I guess those would be on the PSU right?

Use a voltmeter and check the rails on a free 4-pin molex connector. Black = ground, red = +5V, yellow = +12V. If they're not within +-5-10% of what they should be, or they fluctuate a lot (more than +- a couple percent), that's a bad sign.