Hey all! So i scored myself a Mac Pro 4,1 (Early 09) 8 core setup, it had a Quadro 4000 2GB and i wanted to swap it with my GTX 660 3GB from the 3,1 Mac Pro i have, so i went ahead and swapped everything over, moved the hard disks out of the 3,1 into the 4,1 as well, pressed the power button, got the chime...then nothing. I knew there would be a black screen because of the GTX 660 being a PC card but i waited a good 20mins just incase it was doing something...nothing. I shutdown, i put the Quadro back in and suddenly its booting again... If i have the Quadro AND the GTX 660 installed, again, perfect boot and i can swap my TV between the two, and the Mac recognises both are there, latest Web drivers for 10.9.5 are installed. But the Mac Pro seems to be putting the Quadro GPU ahead of the 660 despite the quadro being in a slower lane (4x vs 16x the 660 is in). Anyone got any idea why this is happening? If not, does anyone know if its safe to have 2 GPU's like that? I'll happily leave the quadro in there since it seems to be the key to booting the Mac, but will it takeover the 660 in terms of my work? (I do video editing and occasional gaming). Any info is appreciated!