New system not posting...

[(electricskyline)]

Hey everybody,
I just built a new system, and it is unfortunately not posting. I've tried everything I can think of, so I'm here looking for suggestions. Here are my specs:
AMD Athlon 64 3000
1Gb Corsair XMS DDR400
300Gb Western Digital SATA Hard Drive
ASRock 939Dual-SATA2 Socket 939 (ULi m1695 chipset)
Koolance CPU-300-H06 Waterblock in a Koolance PC2
DVD and CDR drives
Coolmax CX400B 400W PSU

It turns on, but does not post, and won't turn off. Any suggestions?

Thanks!

 

[Slartibartfast]

pull out everything except cpu and 1 stick of ram, (maybe videocard, some mobo's wont post without one), and if it posts keeping adding devices one at a time until you find what breaks it. if it doesn't post, try another psu