Why at the top of the card slot with the

My 8800GT is at the top of the card has a 13 Goldfinger's why plugs used

the formation of the SLI dual graphics cards When used.Two graphics cards for increased bandwidth connections.In your computer's graphics slot on the motherboard plug on two graphics cards, SLI used a cable to connect two graphics cards Up.This will enable the two graphics cards together.A specific reason not say here, so a professional (frame involved, the refresh rate, the quality of bitmaps, memory, etc.).Is the specific role of the two Block graphics co-ordination and function of superposition of two graphics cards together.