Boots sometimes and shutsdown when installing Windows

This is the third build I have done. When I turn the computer on, half of the time it boots fine and half of the time it shutsdown after 1-2 seconds. If it shutsdown, it automatically tries to boot again after 5-10 seconds only to fail and try again. If it boots fine, I try to install Windows but it just shutsdown 1-2 mins in. It even shuts down when I'm browsing around the BIOS. All of the case fans and cpu fans are spinning and connected. This is a time sensitive build so quick responses would be greatly appreciated.

Specs:
Intel i5 2500k
Corsair 650TX
MSI P67A-GD65
Patriot Gamer 2 Series 8GB 1600 mhz
XFX 6870
Western Digital Caviar Black 500 gb
HAF 912

Steps tried:
1. Reapply Thermal Paste (used coolermaster brand)
2. Reconnect all power connections
3. Swapped with a set of ram that I know works
4. Reseat/remove GPU
5. Manually setting ram timings in BIOS
Note: With this particular motherboard, the POST beeps indicate the number of USB devices connected, not any diagnostic function.

Thanks for any help in advance!