I have a late 2013 iMac...with an NVIDIA GTX780M video card.  I recently installed Catalina...the new MAC operating system (wish I hadn't)...and now my video card doesn't seem to work.  I checked my system...and according to Apple my system is up to date.  I called Chief Tech Support...they told me that Apple controls the drivers on their systems...and Chief doesn't have a solution.     So...wondering if anyone else has this problem and maybe has a solution?  Or...should I just head ou