MSI ATX BX13 User Manual page 36

The mainboard provides one 5-pin infrared (IR) connector for IR modules.
This connector is for optional wireless transmitting and receiving infrared
module. You must configure the setting through the BIOS setup to use the
IR function. FIR and Consumer IR are reserved functions.
2-31
IRTX
GND
IRRX
NC
1
VCC
IR