A coworker had one of the Samsung 28" displays, and let me test it with my MacPro 4,1 with a flash 7950. It *almost* works - I actually get 3840x2160x60hz, but with some display corruption on the last ~100 pixels on the right. Oddly enough, I can mirror the display to my Seiki 4k (30hz) and it looks fine on the seiki, corrupt on the samsung. Under windows, everything looks fine. Has any managed to get 3840x2160x60hz in a classic Mac Pro?