I am having the same problem. I have updated the bios and tried several versions of radeon vega 8 graphics drivers and none will stop the screen from flickering off for sometimes a second and others for more then 30 seconds.
the windows basic driver works for the video but then I lose the audio through the hdmi.
I have the Asrock B450m-hdv r4.0 motherboard and their tecs don't know if it is a MB issue or a ryzen problem. I will have to send them back the M-board to find out.
If your board is different, then it is probably a processor flaw. My G-force video card works fine but I did not buy this setup to have to run an exterior graphic card. Kind of defeats the whole purpose.
