Though based on the Radeon X1800 XT part, the CrossFire master boards have a slight change in their specifications. The clock speed of its graphics chip has remained the same, a frequency of 625 MHz; yet the 512 MB of onboard GDDR3 memory is set to 720 MHz rather than the 750 MHz clock speed found on standard X1800 XTs. Aside from this slight decrease in memory speed, the master board otherwise appears identical, mainly because its heatsink occludes the compositing chips that makes CrossFire work. While ATI has developed various rendering modes to enhance game performance for CrossFire owners, the master and slave boards communicate through an external DVI Y-cable, or dongle, that transmits the slave board's output to the compositing hardware on the master card..



Link: SimHQ