Do you know which motherboard you have (eg P5N-E 650I SLI).
I should think it's probably a motherboard issue - maybe you got a dead one, or a PSU problem (there are normally 5V and 12V leads for PC's. Make sure you have the right one. Usually on Asus boards, there is a little light which turns red if not enough power is being supplied.
First thing to do would be to visit
www.asus.com and download a manual for your motherboard. The shipped ones are usually wrong, have misprints etc. Check all your cables are connected properly, and try booting and installing with only one stick of RAM first. If you're HDD's are in RAID, you could try and boot with one connected via SATA.
If you're sure everythings connected properly, and you tried the RAM, contact Asus and see what they have to say. If you can't work out a solution, RMA the board. But do check other possibilities out first.
Hope this helps
EDIT: Ah, beat me there Cohen.