This Graphics Card system requires a Crossfire-compliant Motherboard with a pair of PCI Express (PCIe) graphics cards, which can be enabled via either hardware or software. Radeon x800s, x850s, x1800s and x1900s come in a "Crossfire Edition"' that has "master" capability built into the hardware. So you need a Master card, and pair it with a normal card from the same series. Radeon x1300s and x1600s have no "Crossfire Edition" but are enabled via software. ATI currently has not created the infrastructure to allow FireGL cards to be set up in a Crossfire configuration. Another point to note is that the "slave" graphics card needs to be from the same family as the "master", regardless of whether the master is designated by the hardware or by software, ATI`s Catalyst.
With the release of the Radeon X1950 Pro GPU, ATI revised Crossfire's connection infrastructure to eliminate the need for past Y-Dongle/Master card and slave card configurations for Crossfire to operate. ATI's Crossfire connector is now a ribbon like connector attached to the top of each Graphics Card, similar to nVidia's SLI bridge, but different in physical and logical natures.

Crossfire – Click on image to expand


Note - Crossfire is good at high resolutions and single new high end Graphics Card is capable of playing about any game on the market.

More on Crossfire > Here