I had a brilliant plan to upgrade my Mac Pro from Mountain Lion to Yosemite...bad idea. It was a clean install with the stock 8800GT, turned on FileVault and swapped back in my 660Ti, thats when I ran into trouble. With the PC NVIDIA GPU under Mountain Lion with FileVault2, I would normally decrypt the disk "blind" by just typing in the right keys and hoping the sequence was right. Under Yosemite, the same typing-blind trick wont work any more. The machine simply wont boot with ONLY the PC GPU installed. I spent over an hour swapping hardware and I was finally able to boot with the PC GPU after turning off FileVault (with the stock 8800GT). Is this a known issue? I couldnt find any reference to it in search.