I don't have any Sapphire Nitro+ RX 580 4GB cards, but I know my Sapphire Nitro+ RX 580 8GB SE cards with a Samsung/Hynix dual memory Bios don't like a core clock over 1150 MHz. If I increase the core clock by more than that, the hash drops. I use the Polaris Bios Editor v1.6 from jaschaknack, 'one click timing patch' Bios mod with a 1150 MHz core clock, 2100-2200 MHz memory overclock, -15% power limit and -96mV undevolt and get 30+ MH/s ETH + 850 MH/s DCR dual mining with a -dcri 28 setting. You also need to use Afterburner v4.40 beta 16 or higher to be able to set the power limit and undervolt with the blockchain drivers.
https://github.com/jaschaknack/PolarisBiosEditorhttps://www.guru3d.com/news-story/download-msi-afterburner-4-4-beta-18.htmlAlso set your virtual memory on Windows to at least 16GB if you're using multiple GPU's.
Soz my bad English, I bought 8 of these cards, can you please answer some questions?, how much watts its pulling each gpu from the wall? What temperature are they handled? Wich one of the two bios are you using when moding? do you thing this are better than msi gaming x??