Windows 7 Home - Cold boot issues

Hi there.

I am having some pretty strange problems with my newly built PC. I was having the same problems with complete formatted Windows vista 64 and now newly formatted Windows 7 Home Premium. This computer has the OS on it, and a few games, nothing else. I do not go to compromising websites, it is used for gaming only.

Problem:
1) I start the computer and it turns on, but never really starts the hard drives. The computer screen stays blank.
2) I power it off by holding the start button for 10 seconds. I wait for the fans to stop, then I start it again.
3) Repeat 2
4) Repeat 2
5) Repeat 2, this time computer starts and I see the screen light up normally. I see post, I get to desktop and everything is functioning fine. After approx 3-10 mins (Depending sometimes it does it sometimes not) the sceen goes blank (computer still on) but it now non functional.
6) Repeat 2, sometimes it will start back up like #5. Sometimes it does not. If I get to desktop, it will not crash now for 10-15 mins
7) Repeat 6 if I get to desktop it lasts longer before it crashes.
8) Repeat 6 Finally it's up and good for 4-5 hours. Usually long enough for me to run my World of Warcraft raid. After about 4-5 hours just out of the blue, screen goes blank, computer is still running. Then I am back to 2)

Very odd problem.

Can someone give me some idea on how to find the error for this? Has anyone else had this problem or similar problem and give me some help please?

Thanks in advance.

Specs:
Windows 7 Home Premium
Processor: AMD Phenom 9950 Agena Quad Core 2.6GHz 4 x 512KB L2 Cache 2MB L3 Cache
Board: K9N2 SLI Platinum AM2+/AM2 NVIDIA nForce 750a SLI ATX AM
Ram: 4 GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 1066 (PC2 8500
Video: BFG GTX280 1024E GeForce GTX 280 1GB 512-bit GDDR3 P
Drives: 2x WD Raptors 74gig 16MB Cache SATA 1.5Gb/s 3.5" Internal Hard Drive - Raid Zero
Ram: CORSAIR CMPSU-750TX 750W ATX12V / EPS12V SLI Ready

Glad you got that sorted out!