Asus Z9PE-D8 WS Manual page 55

5. Power supply SMBus Connector (PSUSMB1)
This connector supplies power for low-speed system management
communications.
6. Serial port connectors (10-1 pin COM1/COM2)
These connectors are for the serial (COM) ports. Connect the serial port
module cable to one of these connectors, then install the module to a slot
opening at the back of the system chassis.
ASUS Z9PE-D8 WS 2-33