Asus Z9NR-D12 - Manual (Page 57)

ASUS Z9NR-D12 2-37
11. Power Supply SMBus connector (5-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.
This connector functions only when you install the ASUS ASMB6.