Well, When I upgraded to a 8800 gts video card, my computer would randomly shut off. So, I took the 420W power supply out, and put in an OCZ 600w power supply. I haven't had that happen since.
I also had no BSOD when it would shut off. It would all die at once. Especially when I was watching a bluray movie...
I would recommend going away from an asus motherboard, and possibly going to EVGA...

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All it takes for evil to prevail is for good men to stand by and do nothing.

Too many people tip toe through life, never attempting or doing anything great, hoping to make it safely to death... Bob Proctor

'95 S320 LWB
'87 300SDL
'04 E500 wagon 4matic