Final Cut Pro X - Graphics Card Coice

I am looking at getting a second hand Mac Pro 2010 and upgrading, however one thing I am unsure of after looking at the benchmarks and reviews is which is going to be the better card for use with FCPX.

7950 Mac Edition

or

GTX680 Mac Edition

Machine is going to be used for FCPX and Lightroom, DVD/Bluray ripping. No Gaming on it, so not fussed about the Gaming Performance of the Cards.

From what I can tell of the reviews then Lightroom doesn't really use the GPU that much and FCPX uses OpenCL, rather then CUDA.

Especially with the new Mac Pro using AMD Cards then I am leaning towards the 7950 Mac Edition over the GTX680, however would like some advice.
My monitor is a Dell 3008WFP @2560 x 1600 if that makes a difference to what people would advise.

Or would I be fine for what I am doing with the stock 5770 that comes with the Mac Pro 2010.

Many thanks for answering on this one. I will likely initially just be using a GoPro3 camera, however it can shoot at 1080p.

Having read the threads in the Mac Pro section about people having some display issues with the 7950, and your answer, then went with a 680. Where I normally buy my IT kit from seemed to have stopped selling the 680 Mac edition, but I managed to track down somewhere selling a Zotac 680GTX 4Gb which is a 6+6 pin Power Connection.

With the 680's disappearing quickly from the online stores in favour of 700 series and unclear if there will be future GPU Cards released with the new format in the next Mac Pro then even if overkill for now, I should be OK if advance to more advanced camera's.