no CPU mining, just GPU, am mining also with nicehash, when it mines ETH i cant get past that 36-40 Mhashes on my 1080 Ti, i thought this card can do 50 ETH ! spite being liquid cooled and really running cool ! not sure why !...
To mine with GPU, you don't need strong CPU or 100% of cpu power, usually people mine with CPU + GPU, you only need 1 or 2 cores, and it's good enough
About you card, which miners you already tested?
Did you try Nicehash and let the program run all benchmarks?
But to help you, give more information, about how much overclock you reached on memory