GPU, PSU, mobo? What's wrong with my computer?

[nebby86]

This is my first post, so I apologize if it's in the wrong section. Here's the deal:

Day 1: I left my computer on, idling, and went to work. When I returned 4 hours later, my monitor had no signal and the computer was making an awful whirring noise (like a drive/disc spinning up). I killed the power, and went to bed.

Day 2: I was playing a game. About 90 seconds in, my display went out and the whirring started again. I killed the power, opened up the computer, turned it back on, started up another game and watched to see what was going on inside. The display promptly went out again and then the GPU fan started spinning like crazy. The third time I tried this, I logged the GPU temperatures. They were ~50-70 during gameplay, then shot up to 509 (impossible, no?) and the computer restarted. The same thing happened once more, so I shut down for the night (these would be the first and last times my computer behaved in this way).

Day 3: The computer seemed to run just fine (hard to play games in order to test) with onboard video, so I used that for a while. I got my hands on a working PSU. With the new PSU, the computer ran just fine, with and without the GPU installed. No problems gaming, but I didn't test idling with the new PSU.

Day 4: Computer was absolutely fine, gameplay, idle, etc. for a couple of days with the original PSU and the GPU installed.

Day 6: The idle problem returns. I left the computer on overnight, and by morning the GPU fan (I assume it was still the GPU fan) had gone ape-shit, display had gone out. I cut the power and turned it back on and it's been fine since. Of course, I've been using it pretty consistently, not allowing it to idle for more than an hour or so.

Any thoughts? There's much more to the story which I left out for simplicity's sake. Just ask. Thanks.

System:
Antec SmartPower 2.0 500W
Gigabyte GA-965G-DS3
Core 2 Duo E6400
XFX nVidia 7900GS
2x1GB Corsair XMS2
Running XP Pro SP2

EDIT: The entire system is only 3 months old and everything ran absolutely perfectly until "Day 1"

 

[jkresh]

try running dual prime 95 instances for 24 hours (or orthos), then try running 3dmark 06 in a loop for a few hours, then try both and once, report back as to which if any of them crashes the system.

 

[esquared]

Day three was fine with another power supply but everything returned later on when you put the original power supply back? I would put that second power supply you borrowed back in for a few days and see if that day 3 repeats itself. I am only saying this because I've bought two of those 500W Antec power supplies and both needed to be RMAd. Plus, that model, the 500W Smart Power 2.0, really has a bad history to it.

edit:
Also, you said you did ran it with and without the GPU installed. I am now assuming you have on board video in this motherboard or you had access to another video card. When checking the power supply, keep the original video card in with the second power supply. When you check the video card(s), use the original power supply. Change only one variable at a time so you will be able to eliminate each one as the source of the problem.

 

[nebby86]

Day 3 was just a test day. I had removed the GPU to avoid the crashes, and was using the old PSU (PSU1) and onboard video, which worked fine. To test the PSU, I installed a different PSU (PSU2) and used onboard video. The system ran fine w/ onboard and PSU2. Then I reinstalled the GPU with PSU2. Again, the computer ran fine. So, i went back to PSU1 with the GPU. The computer refused to misbehave. I did everything I could to get in to crash on day 3, that is everythying that had made in crash or misbehave in the past, but nothing worked no mattter which components were installed.

I was attempting to rule out the PSU as the source of the problem, but the computer wouldn't act up no matter what I did, so I couldn't. I hope that clarifies what I did.

Seeing as nothing appeared to be wrong anymore, I left PSU1 and the GPU both installed. All was well for a couple of days, and the problems returned.

EDIT: I left it on overnight again (with PSU1 and the GPU) and I didn't lose the display and the GPU fan didn't go crazy. I'm starting to think it must be the PSU and it's going crazy only when there is some sort of power interruption. If it were the GPU or mobo, would it not have the same symptoms every time my computer sat idle for X period of time?

 

[nebby86]

Originally posted by: jkresh
try running dual prime 95 instances for 24 hours (or orthos), then try running 3dmark 06 in a loop for a few hours, then try both and once, report back as to which if any of them crashes the system.

Ran Orthos for ~8 hours. System didn't crash. Looped 3dmark for a few hours, nothing. Ran Orthos w/ 3dmark, still nothing...