INFO: What is CrossFire
CrossFire, also known as CrossFireX is an ATI graphics card technology that enables two or more separate graphics processors to work together to improve system performance. With ATI CrossfireX, expansion of your systems graphics capability is as scalable as you need it to be. CrossfireX can be implemented using different GPU (graphics processor units) cards that are from the same model family. This gives users the ability to purchase different cards and still gain improved graphics performance.
In order to take advantage of CrossfireX technology, the graphics card and the motherboard have to have the Crossfire support built-in. ATI provides a compatibility chart to help identify Crossfire enabled groupings (below).