I am wondering if I can run crossfire with FX-785A-ZNFC and FX-785A-ZN4L video cards. They are both xfx 7850s 1Gb, but they are different model numbers. Would this make them incompatible?
Spec wise, they appear to be identical. What I would suggest is going to the manufacturer and checking their release notes. It may be that it was just a redesign of their cooler or something simple like that.