Not booting after GPU change
I successfully isntalled a hackintosh last summer on my rig with an old ATI Radeon 7950 GPU. However I had to buy a new one (an ASUS Turbo GTX 960) because the old one was getting too slow. After installing the new GPU however, the hackintosh won't boot. I choose it in my bootloader and after that the normal process starts, but while it's half way through loading the grey bar below the Apple logo it just stops and sits like that until I force it to reboot.
What can I do?