I tweaked my GTX 1070 like this, as suggested by user "Shoo" in a comment here:
http://wccftech.com/ethereum-mining-gpu-performance-roundup/70 % Power
-200 MHz GPU clock
4450 Mhz memory clock
Fan: 55-65 % (depending on temp)
Result are nearly as good as before with less power consumption. I will measure off the wall wattage soon and post it here.
this is my first day of mining from 3 years (earlier I mined btc by 5870 and ltc by r9 2xx)
today I built simple miner on 2x gtx1070 FE
stock win10
stock drivers
ethminer 0.9.41-genoil1.16
I not even put my wallet in this - just unpack and start ethermine-stratum-CUDA.exe
stock speed 42-45mhash
after tweaking (-200 core 4450 mem) i got 57-59mhash stable