What function does the SLI connector provide on SLI supported graphics cards?

What function does the SLI connector provide on SLI supported graphics cards?

The SLI connector enables inter-GPU communication of up to 1GB/s, improving performance by consuming no bandwidth over the PCI Express bus. The connector also provides perfect, digital compositing of pixel data that is asynchronous with the rendering rate, eliminating the need for a separate compositing chip or separate video mixing box/card.

For more information on the NVIDIA SLI technology, please visit:

http://www.geforce.com/hardware/technology/sli/technology