Zotac Mini in the 1070ti or 1080 models (I don't have their 1070 mini and I have severe worry issues about cooling on the 1080 ti model) both work quite well - but I have no idea if the fans are ball-bearing so I'm not buying any more.
1080 is a little marginal on cooling if you push it but better than the blower-type cards by a nose, I've never pushed the 1070 ti version but it should be a tossup on cooling with the 1080 model given the identical TDP.
I just saw a VoskCoin video where his 6 * Zotac 1080 mini manage 3,000 sols (500 sols each). Does this seem a bit low compared to a 1070ti?