Random screen flickering on dual monitors 1440p with Radeon 5700 at startup

Support Graphics & Display
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6

Two solutions:

  1. solution: Switch to GNOME, then no issue with amdgpu and dual monitors 1440p.
  2. solution: amdgpu in kernel and KDE SDDM must set the same screen resolution and refresh rate!
    How → Kernel mode setting - ArchWiki
    Change the config file /etc/default/grub → GRUB_CMDLINE_LINUX_DEFAULT adds
    video=DP-1:2560x1440@60 video=DP-2_2560x1440@120
    It must match the display setting of KDE.

Edit:
—> The correct solution: <—
The RAM is faulty and has broken the whole system sometimes or accidentally at startup.
The faulty RAM must be removed from the system immediately! The issue is gone!
See below: