MSI ATX BX7 User Manual page 54

The JVSB jumper is for setting keyboard power. This function is
provided by keyboard and PS/2 mouse Wake-up function.
1
3
JVSB1
Enable keyboard
power on function
Note: To be able to use this function, you need a power supply that
provide enough power for this feature.
(750 ma power supply with 5V Stand-by)
1
3
5V Standby
2-49
1
3
5V (default)
Disable keyboard
power on function