I found no solution to it, AMD have a ticket open about this.
I tried everything to resolve and under the AMD drivers post I have been speaking with AMDmatt about it and done everything he asked for troubleshooting and even doing new installs of windows 10 and passing over every bit of information I could about the system.
I changed psu's, done a rma on the processor, clean install of W10 in legacy and UEfi mode and also just had minecraft installed with nothing else etc nothing has fixed it . I am yet to test with the latest drivers which are installed but not played they game. Did you have 18.7.1 drivers on? You got the same issue but different screen. Another fix is to disconnect and re connect the hdmi cable as this resolves it again. It's also just minecraft I have the problems with and every other game is fine.
Thank you for testing and letting me know.
Maybe
@LtMatt will be interested to hear this too