Browse for the downloaded Windows 11 ISO and click Open. Now, click SELECT under Boot selection to select the Windows 11 ISO file.Enabling CSM Mode causes quantifiable performance degradation and should never be enabled (even when this answer was written, there were only a few distros lacking EFI boot, with all gaining EFI boot by the end of 2017 - Windows has supported EFI boot since Win7). BIOS and UEFI are not the same things - it's one or the other and CSM Mode is only available with UEFI.
