I upgraded my Mac Pro 5,1 with a used Apple original ATI Radeon HD 5870 graphics card. After installation I reset the PRAM. When the Mac Pro booted properly with the grey EFI boot screen I took a sigh of relief. I ran the Apple Hardware Test twice to make sure everything was ok and it reported "No Issues Found", then I ran the OpenGL Extensions Viewer and tested the card. Two of the tests failed. If someone can tell me what the two failed tests means I would appreciate it. Here are...
ATI Radeon HD 5870 GPU Test
ATI Radeon HD 5870 GPU Test