3 should be ok.
By the way, Rx570 is not very efficient for equihash algorithm.
Try ethereum or crypto night. Also bios mod.
Since I am using an 8-10 year old power supply I was afraid messing with the bios and doing something bad to the card if I wasnt giving the card enough power. I did the bios update once but rolled it back when I realized I was on a old driver version so I updated it to the latest. I will try it again tonight unless I should go to a particular driver. When I did mod the bios and played around with setting in afterburner, I started to see some real low hashrates from 250 to 150 so I revert it all back.
I was going to start mining ETH but didnt spend the time to install the wallet and get my address so I went on with Zcash because I had that address already.