I have used DDU to uninstall, I've used the AMD uninstaller, I've also uninstalled armory crate, I've removed the devices from regedit, i've turned off freesync, changed refresh rates on second monitor.
Yes, common problem. Check this thread out: https://forums.guru3d.com/threads/disabling-mpo-multiplace-overlay-can-improve-some-desktop-apps-fli...
The temporary solution is to disable the MPO. In my case the crashes happened much more often when alt-tabbing/switching monitors (though they werent exclusive to those 2 things), and disabling MPO fixed them almost completely (with the exception of rare mpc-hc with madvr related crashes, but thats a whole separate deal alltogether).
Mine only seems to happen while playing Destiny 2 and Call of Duty MW2 & Warzone 2.0...
I have no had it black screen while performing daily tasks, emails, web browsing etc.
I will attempt the MPO disable this evening, Fingers Crossed.