I've seen a lot of interested people on stats on the new pascal GPU's from Nvidia. I am actually setting up a new farm and did some testing the last few days wither i need pascal or old-style AMD's.
So out of the box the GTX1080 really sucks, so bad i did not even consider trying. So yes them story's are true.
however (!) the GTX1070 is a totally different story, and the reason is different memory. Perhaps its the driver that really doesn't support the 1080 in performance and it might take a while ... but with the price difference its not interesting anyways.
So back to 1070's. If you open the box and leave it stock you can forget running it in windows. Windows 7 just crashes and Windows 10 will run it, but very very poor performance with maybe 1MH/s tops (my i7 internal GPU performs better with 2MH/s)
so now its Linux's time. Out of the box with Genoil's 1.1.4 compiled with Cuda8 (which you need to install + latest beta driver) then you will get around 22 MH/s flat out, no tuning at less then 100Watts
With some basic tuning with SMI (which uses the outdated API and is pretty limited) you can bork it up to 26MH/s at the 118W usage. If you look the base power limit is 150W and can be extended to 170Watts so loads of room to play with. But as said with SMI you really cant and you need the real GPU tuning tools from Cuda. Once going there (and with a big help with a AsI tool trying all the options) i was able to find the highest possible overclocking settings.
pom pom pom, with fully maxed out you can get: 31,92 MH/s using 145 watts (so you can keep the 100% power limit) and with the FAN at max only gets 53C.
I have Asus GTX OC 970's to compare them and those are based with 18MH/s and can be tuned to their TDP max with 22-22,5 MH/s but is using 160Watts at that point. So the 1070FE is 50% faster and still uses 10% less power. You can even get the power down a few watts by tuning the FAN's and set it to like 70% perhaps.
This is all with single cards, my experience with 970's is that combined in pairs you can get a little more (perhaps 1MH/s) and in addition its not a lot of time spend with manual tuning. At some point i was getting 32,96 MH/s but after a few minutes it got unstable. With a lot more time tuning perhaps you can get that extra 1+ MH/s and if you ever get it stable, do post your settings.
Photo's with 36 GTX1070's following soon