Chosen Solution
Hi there I’ve got Mac Pro 2009 flashed to 5,1 (to natively support High Sierra) - I’ve purchased Radeon 7950 because been told it is supporting macOS Mojave - and…. sorry - but got slow window animation “washed” white/grey colours like I’ve seen somewhere on youtube on unsupported Mac (I think 2008). 7950 is EFI flashed. Mojave Public Beta 2 So what’s wrong?
Your other problem may be that the High Sierra and/or Mojave has messed up your hard drive formatting if you have upgraded to an SSHD or SSD. I have the same machine, flashed to 5.1 with DosDude, but I only took it to Sierra. Running a 512 SSD as my boot drive. Also MS Office 2011 will slow you down to a slow crawl with High Sierra and/or Mojave.
Go into About this Mac > System Report. Jump down to ‘Graphics/Displays’ section click on the GPU and look for the heading ‘Metal’ in my MacBook Pro 2012 system I see ‘Supported, feature set macOS GPUFamily1 v3’ Yours should say something similar if it supports Metal. You may only need to update the GPU drivers to get it to work.
