I have replaced my SLI setup of two GTX 660ti's for one GTX 980. I have always thought my SLI setup was pretty good and never have to turn many settings down too much for decent 60 FPS gaming. But I can't help but be completely underwhelmed by the performance of the 980 so far.
I have noticed non to slim FPS increase on the games I play most frequent. Those are Project Cars, Far Cry 4 and Battlefield 4.
It is faster here and there but no where near what I expected, Project Cars was the least improved still only getting 30-60 fps on highest settings at 1080p and I was getting that on my old cards. Also lots of FPS drops too at various points round the track which I think is unacceptable for a £400 gpu.
The new card also suffers from horrid coil whine so without a shadow of a doubt its going back, but I am struggling to decide if I should get a replacement when there is practically no difference from my old SLI setup.
660 Ti SLI should be faster than a single 980