The Mini Din socket is seen in many graphics cards; it allows the signal to be displayed on a TV set. The S-Video standard port consists of a Mini Din connector with four pins / sockets. But is it common to find Mini Din connections with more sockets in some cards. The locations of the sockets are such that a 4-pin Mini Din plug for S-Video can still be fitted in such non-standard sockets.
Mini Din sockets / plugs are also used to carry power signals, and can be seen as power connectors in some devices like external drive bays.