How it Works?
Because ATI does not have an internal connector piece between the two cards, they require an external dongle much like the Voodoo 2. The DVI out of the original RADEON X card gets fed into the CrossFire Edition's DMS port which is basically a digital input feeding the compositing engine. End users however, will not lose the use of the DVI port as ATI will provide a Y connector that will still allow an output. There is system memory overhead to help with the synchronization of the two cards. After each card is finished rendering, the combined output of the video cards is sent out of the video card and shown on the display.

Breaking things down here, ATi is claiming an approximate 25% performance boost in aging game titles like Unreal Tournament 2003. Further they are reporting a ~ 75% increase in the OpenGL based Return To Castle Wolfenstein: Enemy Territory. Lastly we see a near 100% increase in performance for Splinter Cell, which we assume to be the original title, as apposed to the recently released Chaos Theory addition to the series. The main take-away here is that depending on whether the game engine is CPU or Graphics bound, you'll see varying degrees performance improvements afforded by CrossFire Multi-GPU rendering. Again the flip side of that is, if you have a game already running at blazing frame-rates with a single card, with CrossFire you can turn up to new levels of 10X and 14X "Super AA" and see the benefits of the image quality, while multiple GPUs keep up high frame rate. This of course is all theoretical commentary for us at this point.