Asus P5Q-EM - Manual (Page 50)

1-38 Chapter 1: Product introduction
5. IEEE 1394a port connector (10-1 pin IE1394_2)
This connector is for a 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!
You can attach a FireWire/1394 cable to this connector if your chassis suppots
the front panel IEEE1394 port. Connect the 1394 cable to ASUS Q-Connector
(1394, red) first, and then install the Q-Connector (1394) to the 1394 connector
onboard.
The IEEE 1394a module cable is purchased separately.
6. 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 serial port module is purchased separately.