So... there just seems to be no way to use an GTX 970 properly for mining with Win 10 (1703).
after googling and testing for an entire day...
382.33 + CUDA 8.0: 3 MH/s
372.54 + CUDA 6.5: 9.5 MH/s (with P0)
347.52 + CUDA 6.5: 16.5 MH/s (driver won't allow P0 setting)

Why don't you switch to Win7, at least to get it out of your head ? 970
DO hash, not the most efficient results, but this GPU is 3 years old already. Like I said, I learned with 2 of them, and was getting 24MH/s per card, @180W [free electricity, I OC'd them to hellish limits]