Might sound like a stupid question but have you tried reseating the cpu?

Also maybe double check to make sure you wired up the front panel switch header properly on the board.

Assuming the speaker is connected correctly, the CPU is working, the BIOS is good and the CPU is able to run it, then it should be able to beep at that point for any other fault that might be occurring.
Since it's not beeping, I think one of the above is failing. Bad BIOS, bad motherboard, bad CPU are all possible.

If you have a voltmeter, you might try checking voltages. At least check the main voltages but if you know how to go about it you could also look for Vcore on the motherboard's VRM.
Make sure there isn't anything seriously wrong with jumper settings. Try resetting the CMOS if that hasn't already been done. I had one Asus board come to life when I held either INS or DEL (can't remember which) while it was powering up. Apparently that resets some things.
Other than that, I can't think of anything else you can try except another CPU. If you happen to have a POST diagnostic card, it might show you whether there's any CPU/BIOS activity taking place.
If the board is in a weak condition, then a low end CPU might be easier for it to boot. But if that's the situation, you might not want it anyway.

Okay, I reseated everything, including the CPU. I also plugged in all the front panel connectors, not just the power button and PC speaker as I had done previously. No change. Still no beeps, still no POST.

Looking more closely at the CPU, I think it may actually have some physical damage. There's a scratch across the top, and the edge of the die has a tiny chip out of it. I'm going to order another and try again.

Got a new CPU, and now everything is A-ok. The board posts, boots, and runs benchmarks like a champ. Schweet!

Now, to find a home for this awesome motherboard...