Hi Turtle11, I have reinstalled with safe mode on now, but the problems reappears. It was fine during trial, but not after actual installation. Would you know where else I can look at to investigate?
It names in gpu "artefacts" - you can used a google to research what that means.
I have that experience with my gpu amd radeon r9 390 the processor gpu is working ok but one from memory gpu propably is damaged broken - ( i mean ram in gpu) - it propably could be also wrong drivers or temperature. I tried downgrade speed gpu and Mhz maybe will be life longer.
It is hardware issue not a operating system.
The best idea using live usb and backup all important files.
Thanks for your input, @Bourne. It was working on live USB, but not after I performed the installation. the graphic card was working fine when it was in Windows thought. (I migrated from Windows to Zorin today).