This can be very difficult to troubleshoot.
Check everything out. Make sure the board is mounted good, the heatsink and CPU are properly mounted. These shouldn't be problems since you post.
Check hard drives, jumpers, clear the CMOS, reseat the RAM. Pull out all cards and boot without anything than only video. I've had many boards that need to boot without video than with just to get a post. Go to a local shop and get a speaker for your board, they'll probably lend it to you free. They make little tiny piezo speakers with a 2 inch lead and connector on it. great for troubleshooting boards, you don't need the big old fashion car speaker in he case. I think I always got a speaker with my Antec cases...can't remember.
Or rip a speaker out of an older case if you have one hanging around or out of a friends case.
Damn Asus boards, for a company that's supposed to make the best boards I always had the hardest time getting Asus boards up and running for the first time. I gave up on Asus and hate them now.
Good luck to you and exercise patience. Patience is the #1 trate of any good PC tech.