comp shuts down please help

Well i have been playing warhammer online beta for a while with no problems than all of a sudden my computer would shut down. Some times it would be right away when i play and some times it would be after an hour or so. My comp runs fine with every other program so i decided to reformat and now about 10-20% into the installing of windows it shuts off. I have checked all my fans and took off my panels and have a big fan blowing into my case. Have also checked the memory. please help thanks

NVIDIA nForce 680i SLI mobo
Intel(R) Core(TM)2 CPU 6400 @ 2.13GHz (2 CPUs), ~2.1GHz
8190MB RAM
500GB HD
NVIDIA GeForce 8800 GTX
Windows Vista™ Home Premium

 

Well, I see one thing missing from your specs. What PSU (Power Supply Unit) are you running?

E

 

sorry i forgot that it's a 600w

 

Well, I see one thing missing from your specs. What PSU (Power Supply Unit) are you running?

E

 

You say it only happens while gameing then it could be the video card. Recheck the fan there and that the heat sinks are not full of dust

 

yeah it happenes in games and when i try to re-install windows. my graphics card seems to be working fine with no drit or dust and all fans running

 

I would dl some testing tools and run some test
http://www.majorgeeks.com/downloads4.html
I would also run ccleaner
http://www.majorgeeks.com/download4191.html
or my favorite ncleaner
http://majorgeeks.com/nCleaner_d5476.html