I just picked up a second MSI 5770 Hawk and was trying to set up the crossfire on them, but it seems that in any fullscreen app it only ever uses the first gpu. If I run a game with the crossfire enabled in the ccc, MSI Afterburner shows gpu1 at 99% and gpu 2 at 0% and I get no increase in fps. I have tried several sets of drivers and re-seating cards/bridge, and am at a loss as to what might cause this. Crossfire is enabled in CCC and GPU-Z is showing it enabled as well (at x16 each).
*Edit for more info - Each card works individually, I have tried each one alone and they both run fine. Also, I have tried a different bridge, and PCIe slots.