I'm somewhat of a newbie, I want to upgrade my MacPro5,1 and I'm not sure what to do next. Currently running High Sierra 10.13.6. 32GB Memory, 3.2 GHz Quad-Core Intel Xeon and standard card ATI 5770. I just bought AMD Radeon HD 7970 3GB. Flashed to support native EFI boot screen on Mac Pro...