Computer Won't Boot

Hello,

I recently built a new computer and everything was working fine. Last night I turned off the computer, today when I turned it on, all fans, hdd, gpu and dvd turn on but after 3 seconds, the system shuts off automatically (all with a blank screen on the monitor). About 3 seconds later, it will turn back on by itself and nothing appears on the screen. I have cleared CMOS and it booted to BIOS, but once I click Save Changes, it simply gives a black screen, with an orange light on the monitor (can't detect computer). Any ideas what could be wrong?

Mobo: ASUS P5Q3 Deluxe @n Wifi
CPU: Intel Q6700
GPU: IceQ HIS 4670
PSU: PC Power & Cooling Silencer 750W
Case: Apollo NZXT

As well, the case activity light turns on every other second.