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.
I support this, wattman and OverdriveNTool are only ones that always worked for me, direct OC from miners and AB and Trixx get
broken often...only if you don't upgrade drivers, use AB or trixx