Mac Pro 4.1 and LG 31MU97

[hockeyamd]

I just got a good deal on a Mac Pro 4.1 and I am trying to figure out the best video card to run my LG 31MU97. I would like to be able to run it full resolution of 4096x2160 @60 and have retina support if I run it at lower resolutions.

Which graphics card would be the best upgrade?

 

[RoastingPig]

980 $500
970 $300
960 $200
950 $150

All will run the display perfectly