The overclock resulted in a performance jump of 11% at 1920x1200 as frame rates increased from 35fps to 39fps, allowing the GTX 960 to clearly overtake the GTX 760 and R9 280X.
When testing our overclock with BioShock Infinite we see that the GTX 960 became 10% faster, going from 60fps to 66fps at 1920x1200, matching the performance of the R9 285 and R9 280X.
In Tomb Raider we saw a solid 11% increase in performance as the GTX 960 went from 52fps to 58fps, matching the GTX 770 and surpassing the R9 280X.