I recently got my powercolor RX Vega 64 AIR. I have the latest drivers dated 13/11/2017 and I am facing some issues after a couple of minutes playing either forza 7 or forza horizon 3 where rainbow coloured artifacts start appearing and textures seem to not be loaded correctly. I haven't seen those issues on other games and in stress testing under furmark.
Now the other major issue I noticed is my screen losing signal and minutes later my whole system locks up needing a hard reboot. That usually happens on the desktop and I noticed at least 2 times while playing music on youtube. I had no issues like that before with an rx 480 8GB or the igpu.
Any ideas what could be causing those issues ?