So I just built this new pc using the aforementioned motherboard and the first time I booted it up I entered the bios just fine.
I proceeded to install an old release candidate of windows 7 because I didn't know where my windows 7 ultimate cd was and I couldn't wait to test my new pc out for a bit.
When I decided to change my install from the release candidate to windows 7 ultimate x64 I changed my dvd drive to have boot priority over my hdd so it would stop launching into windows, I reformatted and installed and everything was going smoothly.
After I installed windows 7 ultimate x64 and instALLed the ASUS drivers from the dvd provided with the motherboard I can no longer get into my bios, after I turn my computer on ASUS Express Gate loads then it posts after the coundown finishes and no matter how furiously I smash delete it just won't let me access the BIOS anymore.
Could be the wrong keyboard interface (usb instead of ps2 or vice-versa) in the bios settings. I use a wireless keyboard and mouse, and have some lag time until the driver loads. Try removing the board battery with the system off, and check your keyboard connection again.