Huh? But you should be worried about ROI. You do realize that until you reach ROI you are NOT actually making any money. You are not putting any money to work yet because all you did was spend your money. I'd suggest putting more thought into this. There are a lot of risks involved and you could end up losing money instead of "earning passive income."

Anyway, i'd suggest using 1080ti's or 1060s. NVIDIA is much easier to maintain and profit margins now are slightly better than AMD's.