I understand windows won't work with more than 8 gpus of the same brand. By "Brand" I assume the meaning is either amd or nvidia i.e. you can't use an MSI nvidia card if you have 8 other gigabyte nvidia cards.
That being the case, what is the best AMD based card broadly as good as a GTX 1070 in roughly the same price range? This is for nicehash. RX580 seems to be a big step down for mining anything but ether. I'm looking for something that can be underclocked to use around 120 watts. Any suggestions?
I think if you don't want nVidia cards but only AMD, the best is RX 470.
RX 470 is cheapest than RX 579 and RX580 and has the same hasrate.
And the best for the end : RX 470 use less power than RX 570/RX 580 and RX 480.