Correct the ram timing
It is the best way for  ati vga cards

Hashrates are varying on algorithm you use.

RX570: 22 MH/s on stock frequencies and 27 MH/s when overclocked. The power consumption is 115 W and 135 W respectively.

RX580: 24 MH/s on stock frequencies and 29 MH/s when overclocked, with a power consumption of 136 W and 153 W, respectively.

These are hashrates on Ethereum. Ethereum is using EtHash Algo

You can check many things and calculate here : https://www.coinwarz.com/

Also this is a good site for finding Hashrate of your cards : http://1stminingrig.com/

You makes good configurations? Cuz, need some configs