I would first check if the problem you're having is due to not having a clean driver install, or not using the best driver.
This can especially happen when it changed from Catalyst to Crimson. Try uninstalling via the AMD Install Manager, then Driver Sweeper 3.2. Many now use Display Driver Uninstaller, but I've found that it leaves left over bits, which Driver Sweeper's Analyse function shows still on your PC.
I'm using the Crimsons myself on my 7970 no problem, including beta versions.
http://www.guru3d.com/files-details/driver-sweeper-download.html