Fortunately, I never had the opportunity to clear out my CMOS. If my memory serves me right, there are two solder points at the upper right corner of the motherboard (near the memory slots). You have to short those two contacts with something like a flat head (minus) screw driver. I always wondered why ASUS did not put pins in them. It would've been so much more convenient with a jumper.
Getting back to the point, if this method sounds finicky to you, a sure-fire way to clear CMOS is to
step 1) unplug the power cord from your power supply
step 2) push the power button to drain any residual electricity in the system.
step 3) to be on the safe side, reset all your dipswitches to factory default
step 4) pull out the CRD2032 battery (that round, silver coin battery) and leave it out for 5 - 10 minutes.
Hopefully that should dothe work.
Tako_chu