I'm running a GeForce GTX 770, which runs the benchmark successfully at about ~11MH/s, which is what I'd expect from this card.
But when I actually start mining (with ethminer -G) it only hashes at just under ~2.1 MH/s.
I'm running Windows 10. I've seen some posts in the CUDA miner thread about rolling back the NVidia drivers to 347.52, which I've done, but it hasn't helped. Any suggestions besides "roll back to Win 7" (currently not an option....)