Looking for a new GPU to replace my AMD XFX 7850 2GB core edition. Can get either locally for a good price. So which would be better, the 770, the R9 280X or the 960? Note: all are 2GB, bar R9. Which is best for DX11 performance? Presumable the R9. The R9 may not be possible however, so could you put them in best to worst? Thanks!