Hey all, i recently upgraded my mac pro 3,1 ,2 x 2.8Ghz 20GB RAM, to high sierra so far without a hitch. I now have decided to upgrade the card I had in there to something a little better, the HD 7970 3gb which I was running in my 5,1 just fine. I installed it and the computer starts to boot and after the progress bar under the apple logo has ticked about 3/4 of the way through i get hung on a gray screen. I've successfully booted into safe mode with the 7970 installed and go to "About This Mac" and it shows the HD 7970 running what seems properly, but i am at a loss of why its not working through a normal boot up. I have also done first aid to the boot drive and it didn't seem to have any affect. I do have two separate power cords plugged into 7970, a 6 pin and 8 pin(the 8 pin i removed from my 5,1 as i knew it worked). I have also put the old card back in, quadro fx 4800, to see if it would boot normally and it still does. Any help would be awesome.