MSI ATX BX13 User Manual page 50

This is used to check the AGP card or BX chipset temperature. The JT3 is a
2-pin connector which can be inserted with a 20cm length thermistor. It is
located near the chipset heatsink that monitors the chipset temperature. The
BIOS setup for "TOP TECH. II" should be set to enabled.
20CM length
Thermistor
JT3
2-45