ETC mining on Pascal cards seems to be broken. Got only a half hashrate (17-20 MH/s) on 1070ti when mining ETC (ETH is ok).
Tested on Nicehash and Ethermine ETC pools.
I would not say broken, but ETC is in a later dag epoch which may hurt your card more then it should (but its normal etc is slower then eth due to this). I assume at least the general implementation for etc and eth has same quality.