Mining with RX570 4gb

I got an RX570 4gb cheap off offerup. I wanted to see and hoped that it would hash the same as my 580's.

It has been running for two days now and is averaging high 12's to mid 13's mh/s. My 580's stay around mid 11's. Clocks and memory are the same for both the 570 and 580s (1150/2000), and the only difference is the voltage on the 570 is 850mv and is 900 on the 580s. I am running teamredminer on windows 10.

Not a terrible difference, but I am wondering if it is because the 570 performs better on RVN or if I can squeak out another few hash on the 580s. It is hard to believe the 50mv difference makes the 2mh/s difference.

Included a screenshot. I am still fairly new to mining, so I def dont know it all.

I am going to add five more GPUs and switch over to Linux this weekend.