A new ATI advisory is out, and it looks like ATI fans are in for an interesting surprise; X1300 and X1600 won't need a master card. We confirmed this with a few AIBs over the last few hours, but it appears that ATI will release a new driver soon that enables Crossfire over the PCIe bus on Radeon X1300 and X1600 video cards - eliminating the need for dedicated master cards.
Low end NVIDIA cards can already run in SLI mode with out any additional support. Even on high end cards, the SLI bridge can be removed with a performance hit. These bridge-less, cable-less Radeons will represent the purest vision of a multi-GPU configuration. Rather than purchase a BBA (Built By ATI) master card, any AIB or BBA Radeon X1600 will work together in Crossfire mode. AIB partners could not confirm as to whether separate graphic card families would also work together in Crossfire mode.
Radeon X850 and X1800 will still require a master card to enable Crossfire. Radeon X1300 video cards are already filling the channel here and there, but Radeon X1600 is still not expected to hit channel shelves until December.
http://anandtech.com/video/showdoc.aspx?i=2594