Asus RS100-E6/PI2 - Manual (Page 56)

Chapter 4: Motherboard information 4-10
6. Serial port connector (10-1 pin COM2)
This connector is for a serial (COM) port. Connect the serial port module
cable to this connector, then install the module to a slot opening at the back
of the system chassis.
5. Serial General Purpose Input/Output connector (6-1 pin SGPIO1)
This connector is used for the SGPIO peripherals for the LSI MegaRAID and
Intel Matrix RAID SATA LED.