MSI MS-5156 Manual page 38

A battery must be used to retain the mainboard configuration in CMOS
RAM. To retain the on-board battery you must always short pins 1,2 of
JBAT1.
Note: You can clear CMOS by shorting 2-3 pin, while the system is off.
Then, return to 1-2 pin position. Avoid clearing the CMOS while
the system is on , it will damage the mainboard.
3 1
JBAT1
(Default)
2-32