I want to take a ghz edition 7970 from my 7950 rig and run it on my 280x rig. When I replace one of the 280x cards with the 7970 card using the same riser and pcie slot, neither cgminer nor afterburner recognize the 7970 - the 2 280x cards start and run normally. I get no video out of the 7970, the only sign that it's even connected is the fans spin at idle. The 7970 runs fine on cgminer and afterburner on my other rig. I checked the AMD site and the drivers for the 79xx and r9 2xx series are exactly the same. What could explain this and what should I try?