I really don't know why some people on here think that AMD are light years behind Nvidia with the last few generations of GFX cards. All the generations since the 290 haven't been THAT far behind the equivalent Geforce cards.
IMHO it has mostly been down to Nvidia's stronger market share and leverage with game developers than anything related to hardware engineering. I mean if the push towards bare metal APIs, Parallel Queues and Async had taken off in 2013 then we may have seen a market share change before now.
Nvidia's tech does lend itself to extremely high clockspeeds and that is what has helped to keep them ahead. However, I don't think a brute force approach will do that for much longer (Nvidia may prove me wrong on this
) as we see the 1080 struggling to go much faster than 2.1/2.2 on water and it does 2.1 on air (if you get a good one).
The way some people on here talk you would think that Nvidia were two generations in front.