PC Randomly Shuts Off

dahlkomy

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Dec 13, 2012
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My PC shuts off randomly. At first, I thought it was overheating. It was running at 70+ under heavy stress. So I bought a couple more fans and a new heatsink. Now it's running at 40 C under heavy stress, but just shut down again.

It's my first build I completed in June. I bought the CPU, motherboard, and RAM used from a friend. The shutting down problem has only started happening within the past month. Before that, the only problem it has is it takes a few seconds before booting up. It will click, but nothing else, then it will beep and start up. While starting up Windows, it will occasionally freeze and I will have to reset it and try again. It also froze upon waking up from sleep or hibernation, so I just turned that feature off so it never sleeps. I just turn it off if I'm not using it.

I ran Chkdsk last night; no errors reported. I ran Prime95 for the whole night; no errors reported this morning. I just ran Memtest86; no errors reported. After Memtest, I came into Windows to Google around some more and the PC shut down on me again. It usually does it under stress, like while playing a game, but it has happened a couple times in Windows.

When it shuts down, it turns completely off. No BSOD, no restart, nothing. I have to push the power button to start it up again.

I have no idea what's going on.

Windows 7 Ultimate
Gigabyte EP45-UD3P Mobo
Intel Core2Duo E8500 3.16 GHz
4 GHz RAM
GeForce GTX 550Ti
Corsair 650W PSU
 

eshepard

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Aug 17, 2010
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The fact that it happens under stress suggests power to me. When you say stress can you be more specific?? You mentioned gaming, gaming taxes the GPU, which is by far your most power hungry component. Does it ever shut down under intense CPU load when the GPU is under relatively low load??
 

dahlkomy

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Dec 13, 2012
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It has shut off when I'm just doing things in Windows explorer. I ran Prime95 overnight. That's supposed to stress your CPU, correct? Nothing happened all night when it was running.
 

eshepard

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Aug 17, 2010
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k, I am still thinking power. I was asking about GPU load because if it had a tendency to only crash when the highest power consuming component was stressed, that would be good evidence of power shortage. I am still thinking power, but now more because a lack of other ideas. Sorry I don't have more for you.

I don't know of any other reason a well functioning computer, without any other symptoms, would just power off. Sounds like intermittent power outage.

To get real basic, it's possible there is a power spike/drop in the outlet, and that is unrelated to your build. The symptoms described sound like momentary power outage to the system.

I assume when you restart after the power outage it alerts you that windows did not shut down properly??

do you have the pc on a power strip? if so put a lamp on the same strip, see if the lamp flickers when the pc dies, that would confirm an electrical problem.

I actually think it's a pc issue, not electrical, but you have to cover your bases, occam's razor and all that, and I don't have any other specific ideas
 

dahlkomy

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Dec 13, 2012
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Thanks for the advice. I'll try out the lamp technique.

Yes, I do get the "Windows did not shut down properly" message upon restart.

My monitor is plugged in to the same power strip, so wouldn't that be affected by an electrical failure?

Could it possibly by a motherboard problem? I'm thinking it's power, too, but just trying to consider all possibilities.