I'm guessing your RX570 is a 4GB?
As I wrote above, I tested it on a 470 8GB and did not change its hashrate.
They Are 8 RX 580 8GB I'm overcloking using bios. I did try to overclock the memory and core using afterburner beta 4.4.015 as well as undervolt for one of my card and it took the new settings.
I have my monitor connected to a GTX 1070 and use it as my main card for the monitor.
Update afterburner 4.4.015 took the new under volt settings but it goes up and down. So I will stick to making the changes on my bios instead .