So according to Apple, at the time of upgrade from High Sierra to Mojave, you had to give up boot screen support for ALL graphics cards in a Mac Pro. At least, that's how I remembered the initial announcement during the Mojave beta period. And I was so frustrated with Apple that I created a radar bug complaining about it, even going so far as to take a picture of the box of the Mac Edition Radeon 7950 box that has the "designed for Mac" logo on it. I told Apple that it was unfair for them to break existing, important functionality on hardware that was specifically certified by Apple as being fully functional.
Later, when I finally upgraded my 5,1 MP to Mojave, it seemed like boot screen support had indeed gone away. Then, I'm not sure exactly which Firmware update did it, but with the Mac Edition (EFI-based) 7950, it seems that boot screen support had returned. I discovered this when I tried to hold down Option to see the boot picker, and magically it worked.
However I never heard any official word from Apple that this functionality would be preserved for compatible, EFI-based cards. Can someone on this forum please confirm that this is actually expected behaviour? Does the latest 144.0 firmware support boot screen visibility on the DVI port when using a designed-for-Mac EFI-based video card like the Sapphire Mac Edition 7950?
Later, when I finally upgraded my 5,1 MP to Mojave, it seemed like boot screen support had indeed gone away. Then, I'm not sure exactly which Firmware update did it, but with the Mac Edition (EFI-based) 7950, it seems that boot screen support had returned. I discovered this when I tried to hold down Option to see the boot picker, and magically it worked.
However I never heard any official word from Apple that this functionality would be preserved for compatible, EFI-based cards. Can someone on this forum please confirm that this is actually expected behaviour? Does the latest 144.0 firmware support boot screen visibility on the DVI port when using a designed-for-Mac EFI-based video card like the Sapphire Mac Edition 7950?