This is what I do - despite what people say on Windows 10 you don't need dummy hmdi plugs, instead if your motherboard supports it force on-board graphics (so no graphics go via the cards you are mining with), and allow Windows 10 to detect the cards in device manager normally.

When adding new cards always and I mean always (this has cost me hours) uninstall the AMD drivers with DDU, then install the blockchain drivers fresh.

Lastly I've had much better results for AMD cards with OverdriveNTool instead of Afterburner etc.