How to completely reset GPU settings

[skiffx]

Is there a way for OSX to completely reset GPU settings, IM having trouble running MP5,1 and Radeon 7950 after plugging in a 5K monitor the old monitors wont detect, only one a time. I tried removing /Library/Preferences/com.apple.windowserver.plist and same in user's folder and still wont work. I think it might be a result from SwitchResX that Ive removed as well. How do I do an equivalent of Windows' reinstallation of drivers short of doing a clean install ? Thanks!!