I fixed it with : GRUB_CMDLINE_LINUX_DEFAULT="quiet splash iommu=pt"
solution from: panariga https://askubuntu.com/questions/1239149/graphics-glitches-and-artifacts- with-ryzen-5-3400g-apu -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1848741 Title: [amdgpu] Ubuntu 19.10 horizontal graphics corruption on AMD Ryzen 2500u (Raven Ridge) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1848741/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs