Driver should be fine, although it's not up to date as Adrenalin driver for other AMD cards.
If problem gone with generic windows driver then there is issue with gfx chip inside AMD processor.
What you can try is to take off one DIMM and try it with just 4 GB RAM, if nothing changes, try the other stick.
You can also try to set in BIOS DIMM sticks to be running lower then 3400Mhz, for example 2133 - 2400 Mhz for a start, if anything changes.
Make sure your CPU is not overheating, CPU voltage should not be over 1.3 - 1.35V for a start. (if you keep all Voltages on Auto, sometimes it set voltage too high, depends on mobo bios)
might be ram frequency, drop it back to frequencys AMD recommends first then bump it in small increasements. To me its something or setting on your motherboard, its not your monitor if its working fine. Another idea is done run Your monitor drivers Disable you monitor drivers load up your Graphics drivers to suit your CPU & see if the issue goes away. Might be a conflict between your monitor drivers & Radeon drivers can happen. I dont & never do monitor driver updates as i see no point & your graphics chip should control all of that.
Thanks everyone! it appears to be Ram speed issue. (Patriot Viper DDR4 3400). The motherboard says it only supports up to DDR4 3200, but ASUS drivers are ready for Ryzen refresh and detected and ran the 3400 ram automatically. So first I backed the ram speed to 2133 and it was fixed. Then 3200 and the flickering was still fixed and seemed fine, but i got BSOD. So settled for 2800, and that was working fine all day, played some Steam games (Gravel/DOTA). Gravel looked great defaulted to ultra 4k but it was unplayable, about 1fps. Then I put the settings @ lowest and it still looked like arcade quality and its a lot of fun to play, with only occasional slowdown here and there. I'm not a gamer but this was a lot of fun, like getting a free xbox with my workstation.
After this I bumped up the ram to 3000 but it didn't change the occasional slowdown in gravel. Been running good so far.