Asus P5 Qc Build help

[Darthvan]

Hi I'm doing this for a friend of mine. He got an Asus P5 Qc with Intel Q8300, 4 gigs of ram DDR3, N vidia 9800 OC(512mb). 1 Tb hard drive. We got everything hooked up,and started the rig.......................nothing happened,we checked the wires double checked everything,but still can't find a reason for it not to boot. it just sits there,fans spinning,and nothing else !!!.................does anybody have any ideas, because we sure as hell are stumped!!!.Thank you.