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The CMOS memory
The BIOS uses the CMOS memory to store all the settings that have been made
through the BIOS Setup pages.
Battery
The CMOS memory remembers all settings, even when the system is switched off,
by use of a 3V Lithium battery. If this battery runs low CMOS is unable to keep its
settings and you will need to replace the battery. The BIOS will give you an error
message wgen it detects a low battery voltage. The error message ‘CMOS
checksum error’ may also point to a low battery problem.
Restoring default settings
You can load default values into the CMOS memory by selecting ‘Load
Optimized Defaults’ in the BIOS Setup. If you need to force the CMOS settings to
default without entering the BIOS Setup page you can use the JBAT1 jumper. For
the location of the jumper and the battery, refer to the following picture:
Battery
JBAT1
Normally JBAT1 will be in the 1-2 position, this will connect the battery to the
southbridge of the chipset which contains the CMOS memory. If JBAT1 is
temporarily set to 2-3 this will interrupt the battery electricity flow, and the CMOS
memory will be erased, this will however only work if the power supply is not
switched on. Now at the next reboot the BIOS will automatically load the CMOS
default values.
