What driver version are you using? You may want to uninstall the drivers, run driver sweeper and reinstall new drivers. Maybe the 13.10 beta drivers may work. I know cs6 has more issues than cs5 because it's when they first added opencl. Haven't seen any issues with cc yet though. In photoshop, go to edit > preferences > performance. Does it say 7950 and use graphics processor is checked? In advanced is use gpu to accelerate computation and opencl checked? You can also try changing the drawing mode.
Just in case, but did you check cpu/ram usage and temps of everything else?