I get about 30.5MH/s out of each of my 1070s. I use MSI Afterburner to boost the Memory Clock Speed and drop the power level (+600ish on the Memory Clock and 70% of the power). This actually boosted me from like 5MH/s and dropped the power consumption nicely.
I haven't found that secret sauce for the 1080 yet, I'm getting around 25MH/s on that card.
I built the rigs at the beginning on July, so I have a long way to go before I get my ROI.