Built a new computer - Not powering on

G

Guest

Guest
Hey all,
I'm currently putting together a computer for the first time, and I've encountered a strange problem. I've got everything connected correctly (I think), but when I hit the power switch, the computer doesn't fully power on. It will power up momentarily - the fans and the LED on the motherboard both light up for about a second. But then, the system promptly shuts down for a few seconds, before powering on again.

All of my components are brand new, so outside of a defective power source, I don't know what the problem may be. I guess it's possible that I have the power switch cable to my motherboard switched around, but I've read elsewhere that it doesn't matter in the case of ATX systems.

My specs are as follows:
PSU; 600W Thermaltake
CPU: Intel i5-760
GPU: NVIDIA GTX 450
Motherboard: P55-USB3
HDD: 1TB Western Digital
Case: HAF 922
RAM: Kingston DDR3, 4GB

I have no idea what the hell's going on. Help!