Why don't asus include the 'C' submodel firmware in the official S431FL download page - is a mystery in of it self. The ONLY PLACE between the many Official asus websites that I found the CORRECT FIRMWARE download list for my sub-model 'C' is HERE, and currently the latest firmware version available is 203 - which is the one my laptop got. Thus when firmware 204 & 300 do exist for 'AS' sub-model, they are NOT AVAILABLE FOR MY MODEL AS IT IS DIFFERENT SUB-MODEL ! The 'C' postfix meaning my laptop is sub-model C, so firmware that was designed for 'AS' model is NOT compatible with my laptop. the firmware model name for S431FL serie is 'X431FL' - and AFAIK there are two sub-model: 'C' and 'AS'.ī. My laptop BIOS/firmware version is X431FLC.203 ( i.e 203 ), and please note:Ī. I tried to boot with VT-d and CPU virtualization option disabled in the UEFI -> grub gets stuck/freeze.Īccording to THIS SOURCE, such behavior is explained due to CPU microcode fault -> thus it is UEFI/BIOS FAULT -> ASUS FAULT !!!!!ģ. I tried multiple GRUB EFI version (2.20, 2.40 and older ) -> grub gets stuck/freeze. I tried to boot from different USB socket with different USB sticks ( usb 2.0/3.0 sticks )-> grub gets stuck/freeze.

This happens as well with different grub圆4.efi version and releases from different sources: ubuntu, supergrub disk etc. When I try to boot grub圆4.efi of various grub versions ( 2.20, 2.40 ) from FAT32 formatted USB ( like SuperGRUB disk ) - grub loads BLACK SCREEN WITH A STUCK/FREEZE WHITE CURSOR - and the laptop enters NO GRUB MENU/SHELL at all. it is annoying and complicated but still possible. Since NO 'CSM option' available in the UI - I have to 'UEFI boot' any OS. To disable Secure Boot, I had to set admin password -> then delete each of the Secure Boot keys ( not sure if a reboot was needed after saving changes).īUT even after secure boot was disabled -> NO 'CSM OPTION' appears in the UEFI UI menus - even though it is most probably exist & hidden, as the secure boot info reminds that for secure boot to work, csm option needs to be disabled !Ģ. Even though I managed to disable Secure Boot in the UEFI - I don't get the 'CSM option' in the UI so I can't emulate legacy boot ( which I want so that I can boot various portable OSs ). I have two MAIN issues, and another minor:ġ. Recently I purchased VivoBook S14 S431FL.

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