System doesn't start?!

[3nn10]

Hey all, just put together a new machine, here is what I have plugged in and setup:
UD7 motherboard
i7 930 (noctua hs/f)
crucial 6gb kit cas 6
C300 128gb SSD
EVGA GTX 460 1GB (another one waiting to go in)
XFX 850 psu

all inside a cooler master 942

I got it all set up and when I powered it on for the first time everything turned on for a split second and then turned off.
Now the motherboards power button and clear cmos button flash their little blue LEDs and nothing else works... any ideas what is going on?!

 

[treefrog07]

Re-check your power cables to make sure they are properly and firmly installed, including the 8-pin for the CPU.

 

[3nn10]

Best answer selected by 3nn10.