Modding rx570/80s to best mine RVN from ETH?

Hey guys, Before the fork, I was going to switch my smaller rig over to start mining RVN. I have them modded with ETH mining bios/timings. IS there anything I should do BIOS wise for these cards?

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They are 8gb cards of rx570/580 of all different chips/manufacters. Also if you know what OC settings would be best, that would be great!

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Thanks.