iMac (21.5-inch, Mid 2011) w/ AMD Radeon HD 6770M issues following upgrade to OSX High Sierra

Picking up where Jeffmazur left off 6 years ago...I've been fighting with little boxes jumping around my display (mid 2011, 21.5 AMD Radeon HD 6770M) followed by crash.

Using About this Mac System Report/Extensions I found that renaming AMD6000Controller.kext did not keep it from being loaded at startup. So:

1. I restarted into Recovery partition and using terminal, executed command csrutil disable to turn off System Integrity Protection.
2. I restarted in safe mode and using cmd shft . to view hidden files I modified the System/Library/Extensions by moving AMD6000Controller.kext, AMDLegacyFramebuffer.kext, AMDLegacySupport.kext, and AMDRadeonX3000.kext into a new folder called Extensions disabled.
3. Restarted into Recovery partition and using terminal executed csrutil enable to reenable System Integrity Protection.
4. Restarted normally.

I now have a stable display, no little boxes and crashes, but some slow graphics. I was limping along in Safe Mode for years, but found that audio was disabled. Now audio works, videos play, and things seem solid......Thanks Jeffmazur.