So I have a Radeon 5870 and a Radeon 5770 in my pc. Not in crossfire because I read that this is not a valid crossfire setup (Can someboy confirm this?). My 5870 is just working fine, but I can't use my 5770. In the device manager of windows 7 (x64) there is no error, it's all good. When I check CCC, my 5770 is listed under 'Disabled Adapter'. GPU Caps viewer can only view my 5870, so can GUI Miner. Someone has some ideas on how to fix this?
CPU: AMD Phenom(tm) II X4 955
PSU: Coolermaster 620W realpower
You can either install the newer drivers OR make a dummy plug. If you have easy access to the resistors and DVI/VGA connector, I'd suggest the dummy plug because the newer driver cause the CPU to go at full load and so costs you money in terms of electricity wasted.