Asus P5K SE - Manual (Page 53)

ASUS P5K SE 2-29
4. Digital audio connector (4-1 pin SPDIF_OUT)
This connector is for an additional Sony/Philips Digital Interface (S/PDIF)
port(s). Connect the S/PDIF Out module cable to this connector, then install
the module to a slot opening at the back of the system chassis.
The S/PDIF module is purchased separately.
P5K SE
®
P5K SE Digital audio connector
+5V SPDIFOUT GND
SPDIF_OUT