Asus M3N78 Pro - Manual (Page 62)

2-38 Chapter 2: Hardware information
12. 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.
13. Video Graphics Adapter (VGA) connector (16-pin VGA)
This connector is for the onboard VGA connection, allowing you to connect
a display device to your system. Connect the VGA Out module cable to this
connector, then install the module to a slot opening at the back of the system
chassis.
For easier VGA module installation,
install the VGA module to an expansion
slot below the discrete graphics card.
Graphics card
VGA module