Asus P5KPL-C - Manual (Page 45)

ASUS P5KPL-C 1-33
6. Optical drive audio connector (4-pin CD)
These connectors allow you to receive stereo audio input from sound sources
such as a CD-ROM, TV tuner, or MPEG card.
P5KPL-C
5. USB connectors (10-1 pin USB56, USB78)
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.
P5KPL-C
Never connect a 1394 cable to the USB connectors. Doing so will damage the
motherboard!
The USB module is purchased separately.