I have 2 Ati Radeon HD 4870 ( Gigabyte GV-R487D5-1GD and Gigabyte GV-R487-512H-B) and I use motherboard Asus P5K-E Wifi AP.
My Problem Ati CrossfireX disabled ( can't function and can't display in Ati catalyst). Could You help me this my problem? thanks very much. Felix
1. CF bridge is installed
2. Mobo is CF compatible.
3. Cards have same chip
4. GPU Drivers are isntalled.
PS according to my info one of the slots on your mobo is x 16 but second only x4 (2 x PCI-E x16 (blue @ x16 mode, black @ x4 or x1 mode) supports CrossFire). try to lower faster one to x4 and check than.... but anyway its waste of money to run two fast cards on x4 PCIe slots. (x8 is minimum imho)
To get CF working I had to bump my PCIe voltages on my DFI to 100 W.