Asus M4A89GTD PRO/USB3 - Manual (Page 50)

2-32 Chapter 2: Hardware information
Chapter 2
4. IEEE 1394a port connector (10-1 pin IE1394_2)
This connector is for an IEEE 1394a port. Connect the IEEE 1394a module cable to this
connector, then install the module to a slot opening at the back of the system chassis.
Never connect a USB cable to the IEEE 1394a connector. Doing so will damage the
motherboard!
The IEEE 1394a module is purchased separately.
3. Serial port connector (10-1 pin COM1)
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.
The COM module is purchased separately.