Hi David,
Take a look about oc settings on RX 480 and 580´s, these cards need more core mv on cryptonight than eth. It depends the core speed youre mining at.
For example, if you normaly mine eth @1180 and undervolt 800-850mV, in cryptonight V7 you need 950mV at least.
This is not meaning more power consumption, whereas cryptonight is less intensive algo than ethash.
Hope it fix your 0Hs problem with these gpus-
Regards.
Well, don't kick me in the arss when I tell you this but all of my AMD cards are STOCK. Absolutely no MSI Afterburner or BIOS mod on the AMD cards. I have used MSI Afterburner on all my NVIDIA 1080 ti rigs for ZEC to get 700 H/s for each card at 1340 watts for 6 card rigs. But NOTHING has ever been done to my AMD rigs other than the Blockchain AMD driver update.
I have:
8 x NVIDIA 1080 Ti 6 card rigs
2 x NVIDIA 1070 Ti 6 card rigs
4 x AMD R9 380 6 card rigs
2 x AMD R9 390 6 card rigs
1 x AMD RX 580 7 card rig
4 x AMD R9 Fury 6 card rigs
16 x AMD RX 480 7 card rigs
Well... i think you need to work some hours to optimize your rigs. It´s not so difficult and you´ll get much more hashrate and less power comsumption (this means longer life for your gpu´s too).
It´s writen to improve your ether rigs, but there´s a tab with the xmr/criptonight settings.
Regards.