Guys, about the pins. 120W is sufficient for the base/reference models. Then with a factory OC etc you need more. But, with my experience/research on GTX 960, not much.
My model is 128W power limit (EVGA 960 SC 4GB). I can run at 1541MHz + 7400MHz core. However, the power limit is hit in most games/benchmarks. For example, in Firestrike it downclocks 2-3 clock cycles due to power constraints. At stock settings, it downclocks 1-2 clock cycles as well.
However, this may not be a good example because the GTX 960 was initially rated for 2GB, and the 2GB extra for the 4GB models would have definitely increase power on their own by 5W.
Still, I have seen the performance of some GTX 960 like EVGA FTW (most extreme) that comes with 160W power limit, and here in heavy benchmarking use (minus Furmark, that virus!) it tops out at about 85% (i.e. 136W). So yeah, just because the listed power rating is higher, it's mostly headroom that never gets used up unless you run the Furmark virus.
EDIT: As can be seen with the current FE models for Pascals, they OC just as well vs the aftermarkets that come with 2x8pins for example for the GTX 1070. These extra pins really are just marketing gimmicks to fool the unsuspecting. Sure, at the high end it means the core clocks don't get throttled (even then usually just by a couple of boost cycles), but it's gimmicky as hell. I can understand an allowance for 20% extra power than the stock TDP, but anything above that is pure gimmicks.