Hey everyone, I have a Mac Pro 5,1...3.46ghz 12 Core, 64gb RAM....Latest version of High Sierra. Recently purchased and installed an RX 580 Sapphire GPU. Computer does not boot. (Except for Safe Mode, in which the computer does recognize the card) I installed my older GPU along side the new RX 580 to see what was happening and it looks like the computer is freezing about 3/4 of the way into the boot screen. Any advice?