Asus P5Q3 - Manual (Page 54)

2-28 Chapter 2: Hardware information
5. USB connectors (10-1 pin USB 78, USB 910, USB 1112)
These connectors are for USB 2.0 ports. Connect the USB module cable
to any of these connectors, then install the module to a slot opening at the
back of the system chassis. These USB connectors comply with USB 2.0
specification that supports up to 480 Mbps connection speed.
Never connect a 1394 cable to the USB connectors. Doing so will damage the
motherboard!
If your chassis suppots front panel USB ports, you can attach a front panel
USB cable to these connectors. Connect the USB cable to ASUS Q-Connector
(USB, blue) first, and then install the Q-Connector (USB) to the USB connector
onboard.
This module should be purchased seperately.
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.
This module should be purchased seperately.