Asus MOTHERBOARD P5N64 WS - Manual (Page 49)

ASUS P5N64 WS Professional 2-23
16. USB 2.0 ports 3 and 4 . These two 4-pin Universal Serial Bus (USB) ports
are available for connecting USB 2.0 devices.
17. Optical S/PDIF Out port. This port connects an external audio output device
via an optical S/PDIF cable.
18. USB 2.0 ports 5 and 6. These two 4-pin Universal Serial Bus (USB) ports
are available for connecting USB 2.0 devices.