Build shuts off randomly..

[MadPsyance]

I built this pc last month and didn't have a problem with it until a few days ago. It randomly shuts down, and the moment it does..I hear one of the fans getting louder or turning on. I'm trying to keep this short in case it does it while I'm typing this. My specs.

GeForce 7900GS
Intel BOXDG35EC LGA 775 Intel G35 Micro ATX Intel Motherboard
G.SKILL 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel
Intel Core 2 Duo E7300 Wolfdale 2.66GHz LGA 775 Dual-Core Processo
Antec EA650 650W ATX12V Ver.2
Win XP SP3
Western Digital Caviar Blue WD800JD 80GB 7200 RPM SATA 3.0Gb/s Hard Drive

Bios says:
Processor is 47
Intenal temp is 35

is this in the normal range?

[glc]

Yes, those are normal temps. However, they may be higher at the time it's shutting down. I'd make sure you installed the heatsink correctly, the board has to be removed from the case to properly snap all 4 posts down completely.

[MadPsyance]

Awww. you see, when I installed the heatsink, I couldn't for the life of me get one of the plastic screws to snap in place in the mobo. Maybe I'll invest in one of those screw in ones.. thanks for the reply!

[not important]

The stock HSF should be installed prior to installing the MOBO into the case.
Be certain the arrows are properly orientated.
Place your hands behind the MOBO, directly under the CPU, for support while pushing the pins into place.

[glc]

I couldn't for the life of me get one of the plastic screws to snap in place in the mobo.

You should have stopped right there and sought assistance instead of continuing with the build.

[MadPsyance]

I reinstalled the heatsink..correctly this time...and it'll go for 2 hours before shutting down. SAme situation as original post. The temps I got less than 30 seconds after shutdown read 44/35...even cooler than original post. What could be going on here?

[MadPsyance]

Anyone please?

[not important]

What brand and size is your power supply?

[MadPsyance]

Antec EA650 650W ATX12V Ver.2

[MadPsyance]

Ok, I just downloaded a program called PC Wizard 2008 and it says:

Processor Temp: 61 Celcius
Mainboard Temp: 85 Celcius

Processor: Both cores are 48 Celcius
GPU: 60 Celcius
Hard Disk: 41 Celcius

Is this normal?

[MadPsyance]

Upon further research I see that my sensors are probably wrong since I think the computer would have shut down long before 85 Celcius. I've felt the heatsink and the cpu, and neither feel hot to the touch, maybe slightly lukewarm...I'll have to check again right after a shut-down to see if it gets really hot at that time.

For now, I've taken out my graphics card and am using the onboard one and trying to see if that might be the problem.

Can anyone throw out any ideas of what I should test?

[MadPsyance]

Sorry if it sounds like I'm talking to myself here, but:

I've almost concluded without a doubt that it has something to do with my graphics card. I had the mobo's video card running my video all afternoon yesterday. Not a single shutdown. I put my graphics card back in and after 2 hours it shut down again.

At this point I should specify what "shut down" means, cause i never really thought about it much. I lose video, I hear a fan kick on or get louder, but the power light still lights up on the front of the case. Normally when this "shut down" happens, I hold down the power button to totally shut the system off, then hit the button to turn the system back on. Sometimes I can get it running for a few minutes before it "shuts down" again, sometimes I don't even get to my desktop before it does it.

This time instead of immediately totally powering down the system (holding down the power button with the intent to try and restart the computer), I took the side off the case to see which fan was making all the noise...it was the video card's fan!!!

Now, can anyone throw some ideas at me as to what is going on? Is my video card overheating??

I should also throw in some background information. When I built this computer, it was because my old one died on me. I came down here one day, there was no video but the light on the front of the case was on, there was a fan running that seemed to be running louder than usual...it turned out to be my old video card fan. I ended up rebuilding the entire computer..the only parts that are actually original in this new build is the case and the hard drive. I replaced everything else. I concluded that the old psu had fried both the cpu and the video card. I came to this conclusion because when i bought a new mobo, there was still no video, even with the onboard video from the mobo. Then I got a new cpu, and the onboard mobo video worked, but the graphics card didn't.

So now, like I said, I have every part replaced except the case and the hard drive. Sorry to carry on like that but I've trying to give you the whole picture here.

[glc]

If it continues to be stable with the onboard video, get a new video card.

[MadPsyance]

Ok, I just realized something else. I've always had my build about 3 feet below the heat duct in the room. The duct is usually pointed at me (and the build), and can get very hot down here. I don't know the exact temperature..let's say near sauna levels...crap it seems kinda obvious now.

Well, the exact model of videocard I got is notorious for being very hot compared to other 7900's. Maybe the mix between that and the fact that this room is hot as hell has something to do with it. I'm gonna move the build to the other side of my desk and keep the heat vent closed and see if that fixes it.

[glc]

It may be too late - you could already have some toasted components.

[MadPsyance]

Well, I've had the vent closed all day and I just got home from work. It's relatively cool in here. I installed my videocard and I got to the desktop and it just shut down. A few times when I hit the power button, there was no video and the video card's fan was spinning loud just like it does when it shuts down. So I've had it with that card. I'm using the mobo's video now and there's no problems.

I think I can still return it to newegg. Funny thing is, there are no mention of anything like this in newegg's reviews. A lot of mention of being hot, but nothing about shutting down randomly. Thanks for your help! It's all brand name stuff from now on.