So i just assembled my new comp

RIVE
i7-3960k w/H100
16 gig
G.Skill F3-12800CL9Q-16GBXL
Corsair 1200w PSU
Intel 520 SSD 120gb

plugged it in, hit power, its up for about 2-5 sec, then system dies....then after a few more sec it turns itself back on, runs for a moment, dies again. Its gone long enough for the ASUS boot screen to come up before dying, no idea whats going on! HELP!