Computer Shuts off Randomly After 2-5 minutes

Hey all. We had some storms a week or two ago and the power flickered on/off about 5 times but my computer managed to stay on. I have it plugged into a surge protector so I thought everything would be alright. 2 nights ago my computer just randomly shuts off. Every time I boot back up, about 2-5 minutes later it'll just shut off. It'll do this whether I'm just sitting at the desktop with nothing loaded or if I'm browsing the web and listening to music.

My first guess would obviously be the power supply. I bought it on March 04, 2007 so it's not old or anything. I guess the power might have taken it out.

OCZ OCZ700GXSSLI GameXStream 700W

EVGA 680i SLi mobo
Intel e6600 processor
2x 1GB Corsair XMS ram
Maxtor 120gb SATA drive
EVGA 8800 GTS 640MB video
SB Audigy 2 sound
24" Widescreen Dell lcd
Windows Vista Ultimate 64-bit

I've checked the power supply voltages in the BIOS and they're all within +/- 5%. Are there any other tests I can run on it? Do I need to look into testing my mobo?

 

I had a lap top the shut down after running graphic intense programs. turns out my power supply wasn't handling my graphics card . it was unde warranty so they replaced the card. Also had a compaq that had a faulty power supply it would work for a few minutes and shut down for no reason. replaced the power supply in both and no problems since then.

not an expert but it worked for me.
buggabear

 

Yesterday I put my psu in another computer and it ran perfectly fine for over an hour. I've also tried single stciks of ram but it still shut off. I could not put the other computers psu in mine because it can not handle the video card. The ram was not swappable either.