I have the same board in a Cyberpower that I bought a few months back. It had a couple problems from the start, but they didn't seem too serious and I wasn't sure if it was the motherboard or the graphics card. Then the board failed, wouldn't boot or anything. I also found out Cyberppower's attitude about the problem and why they're so cheap. They don't want me to send the computer back to them for repair, but want me to do all the work; take out the motherboard, send it for an RMA, and then reinstall it. Almost may as well have built the machine myself.
Anyway, my point is that while Asus may have done fine in my previous computers, they seem to have a quality problem now, especially with all the stuff I've heard since I bought the board. Wish I'd choosen a DFI. You may have done nothing wrong, you may just have a bad board. Do check the BIOS, just to make sure there isn't a problem there, and check to see if all the connections are right and tight. Like Doolittle said, strip out the periferals and see what happens. Possibly something else is the problem, but be wary of the motherboard.