Windows boot manager EFI

If I clean install Windows 10 via uefi on a ssd, then move the ssd to another new Dell pc that has its bios reset to default, meaning wiped clean and showing nothing in uefi boot sequence under “advanced boot option” of uefi bios.

how does Windows boot manager appear later?

the EFI boot link is already written in the ssd EFI partition.  When I power up the new pc, F12 shows “uefi device name” under uefi boot list, no “Windows boot manager” appearing yet.
F2 enters bios, in advanced boot option tab, click view next to add boot option, then click file name… I see FS0, FS1, FS2 are the three partitions on ssd.  FS1 is the main partition that user sees in Windows 10 file explorer, FS2 is the Windows recovery partition, FS0 is the EFI boot partition.

under FS0 root directory…, there are two folders

(1) boot> which has a file bootx64.efi, the full path is efi/boot/bootx64.efi path.  Firmwares will always attempt to boot that path if no others are configured.

This is the file that F12 detects and shows before “windows boot manager” name is written into bios.

(2) Microsoft>boot> which has a file named “Bootmgfw.efi”.  This file is the actual Windows boot manager file.  The full path is \EFI\Microsoft\Boot\Bootmgfw.efi.

When you boot the new Dell pc using the ssd, it will next automatically add a new boot name to cmos (aka NVRAM) and call that “windows boot manager”.

btw Bootmgfw.efi means boot manager firmware, its link is written into your bios firmware settings and saved there, so next time it always boot from windows boot manager as the first boot device in boot sequence, although it is not an actual device name but a link to Microsoft boot file in EFI partition.