Hi After some reading, I just went out and bought a 280X 3GB to put in my 2010 5.1 Mac Pro. I previously had an ATI 5870 1GB. I didn't flash the card, so I didn't expect a boot screen. I waited patiently as everything spun up. Boot chime on the internal speaker as per usual. Gfx card spins up and everything seems normal. Initial boot was with two displays: DVI and MDp. Then I fell back to just MDp (Apple 24" cinema LED). And then just the Dell 24" via DVI. Regardless of combo, I get two black screens. I was under the impression this would work out of the box, since I'm pretty current? Kind of disappointed. Card is a XFX DD Black edition and it seems nice and isn't too power hungry. It was spinning nice and quiet. It says on board UEFI BIOS. Can it be that it defaults to an incompatible BIOS? Because this SHOULD work, right?