XFX is crap, buy from other brands like Sapphire, Gigabyte, Asus. I will buy more RX 570 Sapphire and Gigabyte, they are cheap, 20 cards per 1200 USD, but I have free energy, a micro hydro generator producing 30kw. If you pay for energy I don't know if it's a good idea to buy cards to mining.
Not in today's market and especially not if you have normal power prices, it's better to just buy the coins today honestly.
It's better mining than buy coins, i have 30kw free energy.