I'll believe that claim if I see it. There is no way they could DOUBLE the performance of a GTX 1080 on ETH while leaving it on GDDR 5x (excessive latency issues), and even if they moved it to GDDR 5 (not X) I doubt they could get it to 50 even with super-upgraded memory timings.

 On the other hand, I've seen 30% power savings quoted for the GP104-100 - THAT seems possible, especially if they "factory undervolt" it at all compared to existing GTX 1080 cards.