If both methods don’t work, the Windows will fail to boot up. If it does not find any EFI boot partition, the firmware will be back on the Legacy BIOS boot method. During the POST procedure, the UEFI firmware will scan all the bootable storage devices on your machine for a valid GPT and find an EFI service partition to boot from.

The firmware in UEFI boot keeps a list of valid boot volumes called EFI service partitions. It is considered as the successor to the Legacy BIOS. UEFI Boot is the abbreviation of Unified Extensible Firmware Interface. If no valid MBR is found on all installed bootable devices, the Windows cannot boot. If no valid MBR is found on the current device, it will proceed to the next one in the boot oder. If it is found, the firmware will pass execution to the boot loader code in MBR that enables users to select a partition to boot from. Once done, the firmware will load the first sector of each storage target into memory and scan it for a valid MBR. When the computer is powered on, the BIOS performs Power On Self-Test (POST).

Legacy BIOS is the boot process used by BIOS firmware, which stores a list of bootable devices installed on your PC on a priority order.

The firmware is software that acts as an interface between the hardware (motherboard) and the OS. On a whole, the Legacy BIOS and UEFI are two different boot methods, and the main difference lies on the process the firmware uses to find the boot target. Steps to convert from Legacy BIOS to UEFI without reinstalling OSīefore trying to convert Windows 10 from Legacy BIOS to UEFI, it‘’s better to first learn some basics.Why convert Windows 10 from Legacy BIOS to UEFI?.

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