computer restarts unexpectedly

[licio]

I have:

2.9ghz cpu
4gb ram
1gb video card
350w psu
no viruses

The computer restarts itself when I am playing WOW, from minutes to hours of running the game. I cannot duplicate this behavior through stress tests where the system runs at 100%.

I have monitored voltages and temperatures without finding a pattern.

The bios is set to NOT restart on power failures.

What can I do to try to isolate this issue?

Thanks.

 

[tiny voices]

What is your GPU and PSU? Chances your PSU cannot power the card properly.

 

[Tradesman1]

Also mobo and actual CPU

 

[licio]

mobo - https://h10025.www1.hp.com/ewfrf/wc/document?docname=c01386897&lc=en&cc=us&dlc=en
cpu - http://ark.intel.com/products/36503/intel-core2-duo-processor-e7500-3m-cache-2_93-ghz-1066-mhz-fsb
psu - http://global.aopen.com/products_detail.aspx?auno=2284
gpu - http://www.evga.com/Products/Product.aspx?pn=02G-P4-2645-KR

I have used the 2 sites below to calculate wattage needed and both of them say my system requires less than 300watts:
http://www.extreme.outervision.com/psucalculatorlite.jsp
http://images10.newegg.com/BizIntell/tool/psucalc/index.html

I have tried :

2ghz cpu
1gb gpu
2gb ram

on the same mobo & psu and the problem continued.

If it was a power issue (failing psu or a inadequate watts) wouldn't the system stay off? As mentioned on the initial post the computer restarts itself, it doesn't stay off. I have set the BIOS to DO NOT restart the system if there's a power failure.

The computer gets power from a power bar, which also powers a fan in the room. On the power bar there's a switch. If I turn the switch from on to off then back to on quickly, I can hear the fan turn off/on. When the computer restarts itself the fan doesn't stop blowing.

Thanks again.

 

[Tradesman1]

Have a feeling it's the PSU, it's only a 350, and that's prob the peak wattage which would mean for continuous use it's prob about 275 or so, also the GPU calls for 20amps on the 12 volt this has about 14

 

[licio]

I hadn't noticed this detail and you might have found a solution. I will later on today replace the psu and see if the issue is fixed.

What I can't understand are the following points (assuming the issue is the psu):
-Why does the system restarts only when wow runs and not under stress test?
-Why does it reboot and doesn't stay off as indicated in the bios?
-Why does the system restart without me experiencing any lag at all? It has restarted even while tabbed out.

Is there anyway this restart might be caused due to software fragmentation or poor installation?
Could anything else cause this symptom, where the computer restarts without error?
Is there anyway that I can reproduce this restart?

Thanks once more.

 

[Tradesman1]

Could be a lot of things, PSU seems most probable, might seee if you can borrow one from a friend to test with