SLI Mode
When running in SLI mode, multiple cards share a given fifo. To "talk" to a specific card you put the following commands in the fifo: 00010010 for card 1 00010020 for card 2 00010040 for card 3 00010080 for card 4 0001fff0 for broadcast Then the following commands will only be picked up by the relevant card.
To share rendering, the screen is split between the cards using good old scissors.
TODO: investigate the bridge/DMA between GPUs.