1070 cards have a 150 watts TDP , so for 6 cards + your system need min 150wx6= 900 watts + around 100 watts for ur cpu/mobo/hdd/mem , so your total system draw going to be around 1000 watts , if you know how to overclock and the same time undervolt your cards you will be ok with 1200 watts psu . I would not use 1000watts psu for ur setup...
Building mining rig to about 80-85 percent of a PSU's capacity is advisable to achieve maximum efficiency and stability .
Some GTX 1070 cards have as high as a 180 watt TDP.
(edit) if that's the MSI 1070 model with an 8-pin AND a 6-pin the TDP appears to be 230 watts, per discussion in another thread.
I'd recommend going with a good-quality 1200 Watt or higher - EVGA G2 1300 or Seasonic X-1250 gold would both be good choices.
Platinum and Titanium are more efficient, but the MUCH higher cost tends to take too long to pay off unless your electric cost is VERY high (and in that case you're probably not going to be very profitable in any case).