Asus P7P55D-E - Manual (Page 54)

2-36 Chapter 2: Hardware information
Chapter 2
7. 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!
8. 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.
The IEEE 1394a module is purchased separately.