I finally had crashe at 110°C and recrash after re trying 3D game . So...
I didnt reinstalled F5 BIOS, just desinstalled and reinstalled 23.2.1 7900 driver, had 1 crash entering 3D game ( supply cut ) and ...
All is back to normal with 84 °C T° junction .
I have always the bug with the 2nd 1080p screen displayed at half of vertical screen .