ATI's Catalyst Drivers v8.2 

ATi's latest Catalyst drivers v8.2 has been reported to allow two totally different HD38xx cards from different manufacturers to be used in Crossfire configuration. It's worth noting that the cards we used have different GPU core speeds as well as different memory speeds. You can download these drivers ... HERE (Vista 32-bit).

MSI RX3870 OC Edition 512Mb DDR4
 - GPU core @ 800Mhz
 - Memory @ 2250Mhz

Asus EAH3850 TOP 256Mb DDR3
 - GPU @ 730Mhz
 - Memory @ 1900Mhz

Installation of the drivers was simple, it's just like installing any graphic drivers as you normally would. As you can see from the Catalyst 8.2 configuration, it correctly identifies the two cards. You could access them separately in the ATI Overdrive section. You can also overclock them individually allowing you to change both the GPU and memory clocks on each card regardless of the other card's settings. However, this didn't give us any performance boost, but we're still pleased to see that you can mix these R670 based cards and set the clocks independently.

In the advanced options of the ATi Catalyst drivers, you can enable the Crossfire configuration as shown below. However, since our two Radeon cards are totally different, the Catalyst setup reports a problem with your Crossfire configuration. This doesn't mean that it's working. To prove that it does work ... all we had to do was to run some benchmarks. :)