Power issues, please helps me.

I built my computer about 3 or so years ago. It's been an exceptional machine, but lately things have been failing on it. This machina powered through games like crisis when they first came out so it's been put through alot of stressful pocesses on a regular basis over the years so I'm not suprised it's starting to show it's age.

Reacently, I upgraded to twin western digital blue drives 500g each I'm raid 0 config. It ran great. I reacently installed 2 new fans for my gpu and my RAM. It ran great or like 2 weeks, untill yesterday it randomly shut down on me. Just loss of all power. I try to power it on, and total loss of power after 2 seconds. I try again, and it stays on for ten or so minutes then dies again. I went through this several times, unplugging the new fans to see if it helped. However, it didn't.

During one of these ten minute intervals, I loaded my nvidia performance moniter, and noticed everything it detected showed "under stress" due to voltages. I went into the bios and reset the voltages,( though I've never changed them in the first place ) but still no results. However, I did notice that if I left my computer on the POST screen, it would stay on indefinatly. But once I started windows, I encountered the power loss issue again.

I'm thinking it's a psu issue, but I don't know for sure. And I don't want to buy a new psu and then that not me the problem.

The psu is an OCZ 700w GameXstream.
Intel core2 quad 2.4ghz
8gig gskill ddr2 dual channel pc-8000 ram
2x western digital blue 500g hard drives. (RAID0)
xfx geforce 8800gs alpha dog edition. 384 mb VRAM.
DVD ram drive
thermal take bigwater liquid loop for the CPu
4x 120mm fans
2x 80mm fans
spot fan for ram
expansion slot fan for gpu.