Your drivers seems to lack quality, heard before, but experienced it myself now.
I have an ASUS 7770 card. The clock doesn't idle down to GPU 300Mhz and Memory 150Mhz which is stock and it used to work. Now GPU idles at 400Mhz and Memory just stays at maximum 1125Mhz all the time. Can't even overclock the settings or underclock, seems they like being on this speed.
I uninstalled properly and installed latest drivers and hotfix as well, doesn't work, but work well with Windows drivers.
Radeon Settings app doesn't install as well, complaints that Qt5core.dll is not installed so can not start the app. I need to manually run the installer "\Packages\Apps\CN\CNext\cnext64\ccc-next64.exe" for it to install with the dll file to work.