Its not the motherboard, I have CF 4870 running here no problem, and the CF control is driver based from catalyst
Everest should show ATI crossfire under GPU and GPUz should show CF enabled, but you say your not even seeing option in catalyst
Just sounds like a software issue. Try uninstalling cat and reinstall. I have 2 bridges connected but its not necessary although ATI said 2 can help with bandwidth - see guruof3d forum
This was early build picture but shows slots, its basically same setup except 4870s are double slot width
http://i122.photobucket.com/albums/o...490800x600.jpg
*You can also check each card individually in both slots before running both in CF. When I was messing with the sata ports underneath the lower 4870 and had one card out CCC recognised the card out and then back in and I didnt need to reload it