Asus P8B-MX - Manual (Page 40)

2-22 Chapter 2: Hardware information
2.6 Jumpers
1. Clear RTC RAM (CLRTC1)
This jumper allows you to clear the Real Time Clock (RTC) RAM in CMOS.
You can clear the CMOS memory of date, time, and system setup parameters
by erasing the CMOS RTC RAM data. The onboard button cell battery
powers the RAM data in CMOS, which include system setup information such
as system passwords.
To erase the RTC RAM:
1. Turn OFF the computer and unplug the power cord.
2. Move the jumper cap from pins 1–2 (default) to pins 2–3. Keep the cap
on pins 2–3 for about 5–10 seconds, then move the cap back to pins 1–
2.
3. Plug the power cord and turn ON the computer.
4. Hold down the key during the boot process and enter BIOS setup
to re-enter data.
Except when clearing the RTC RAM, never remove the cap on CLRTC jumper
default position. Removing the cap will cause system boot failure!
If the steps above do not help, remove the onboard battery and move the
jumper again to clear the CMOS RTC RAM data. After the CMOS clearance,
reinstall the battery.