Asus RS926-E7/RS8 - Manual (Page 68)

4-14 Chapter 4: Motherboard information
10. Power Supply SMBus connector (6-1 pin PSUSMB1)
This connector allows you to connect SMBus (System Management Bus) to
the power supply unit to read PSU information. Devices communicate with an
SMBus host and/or other SMBus devices using the SMBus interface.