on skein i can do 1GH with this beast but you need 90-100%tdp, this card i tried many algo and it work good for skein jha and other algo that share the same spec as these, heavy memory algo are bad for this gpu, it need to be optimized
GDDR 5x has higher latentcy than GDDR 5, which is a large part of the reason why the 1080 and 1080 ti don't perform much IF ANY better on ETH than the 1070 despite having higher memory bandwidth.
There is no specific miner to dual-mine ETH + Skein, but you could always run separate miners for each to try it.