fans cycle on and off

[bcook53]

I am building a new computer. The fans cycle on and off for a few seconds. there is a green light on the motherboard, but nothing powers up. I have swapped out the motherboard and PSU, same results. I now have everything disconnected and taken out the memory sticks, still the same thing. The only thing I can think of that I haven't tried is to take out the CPU and see what happens.

Intel DG965WH Mobo
Intel Pentium D 945 CPU
Antec NeoHE 550 PSU

Any ideas would be greatly appreciated.

Thanks!