I will soon be building a PC for a colleague that will run with two 1070 Strix in SLI. I have planned for an 850W power supply, as the 970 Strix can already burn up to 300 watts (I have an Asus GTX 970 Strix, Intel Core i7 4790K (4.4GHz) installed in my own computer, which also runs on an 850W power supply).
In general, if you don't save too much on the power supply, it's easier to upgrade the PC later! So in this case I would recommend the following power supply (I have installed it several times and it runs perfectly without problems): be quiet! POWER ZONE (850W) (
https://www.digitec.ch/de/s1/product/be-quiet-power-zone-850w-pc-netzteil-631907)
I hope I could help :)
