That means overheating, which probably means an excessive fps rate.
In the launcher Game Settings menu, select fullScreen display mode, Vsync off, cap refresh rate at 60.
If those don't help:
Please attach here your Documents/Paradox Interactive/CK3/pdx_settings.txt .
From your Documents/Paradox Interactive/CK3/logs/ folder, attach here system.log , error.log , exceptions.log
Also in Steam please click on Steam-Help-System Info, and paste everything there into a text file and attach that here.
In the launcher Game Settings menu, select fullScreen display mode, Vsync off, cap refresh rate at 60.
If those don't help:
Please attach here your Documents/Paradox Interactive/CK3/pdx_settings.txt .
From your Documents/Paradox Interactive/CK3/logs/ folder, attach here system.log , error.log , exceptions.log
Also in Steam please click on Steam-Help-System Info, and paste everything there into a text file and attach that here.