As stated earlier a Crossfire chipset is not necessary for the cards to work and addition you don't need to enable Crossfire as you needed to enable SLI with the 7950 GX2s in the drivers. Of course games must support Crossfire or SLI in order for both cards to work properly and there have been some problems in the past with Nvidia more often than not in the lead with SLI titles. That said though ATI was a little late to the game with Crossfire, in all of the latest games we played we didn't run into any situation where Crossfire was not working. ATI has also resolved an issue with multi-GPUs with the Radeon 3870 X2 where multi-monitor support would not work with Crossfire or SLI enabled which is now fixed. One problem that does remain though is that currently two Radeon 3870 X2s will not work together for essentially quad crossfire but AMD says to expect something in March.



Link: AMDZone