Intel SG-81 - Manual (Page 15)

Hardware Setup 2-5
2.3.3. CMOS Memory Clearing Header (CCMOS)
This header uses a jumper cap to clear the CMOS memory.
•
Pin 2-3 shorted (default): Normal operation.
•
Pin 1-2 shorted: Clear CMOS memory.
ATTENTION: Turn the system power off first (including the +5V standby power)
before clearing the CMOS memory. Failing to do so may cause your system to work
abnormally or malfunction.
User’s Manual