Does the GPU artifacts occur any other times besides during game times?
Sometime if the GPU card is overheating could be a major factor in a GPU creating artifacts or the GPU being overclocked causing the GPU to run hotter than normal.
Also a defective GPU card will cause artifacts to occur but generally all the time and not during just playing games.
If it only occurs during gaming which puts a large load or stress on the GPU card it could be overheating during game play if you don't have it overclocked that is.
Is the GPU card's Fan running at maximum when playing games?
Make sure the Manual Fan control in Radeon Pro is set at a aggressive mode and working correctly.
Try stress testing your GPU with a program like OCCT or Furmark Fuzzy Donut and see if the artifacts occurs. If artifact occurs during the stress testing check the temperature of the GPU card. Could indicate a defective GPU card or overheating issue.