Slimebeast on 06 May 2016
I heard they're gonna be only 50% faster than last gen, or specifically, a 1080 will be 50-60% faster than a 980.
That's a huge disappointment that they're only going for the mass market and not offering any 275 Watt/16 million transistors high-end card yet, but we'll just have to wait until next year.
AMD is rumoured to go for the same tactic. Only a 50-60% increase while the tech in fact has the potential for a x2.5 increase. 
