Choose UEFI or legacy BIOS modes while installing Windows. After Windows is installed, if you need to switch firmware modes, you may be able to use the MBR2GPT tool.
In general, we recommend installing Windows using the newer UEFI mode, as it includes more security features than the legacy BIOS mode. If you're booting from a network that only supports BIOS, you'll need to boot to legacy BIOS mode.
After Windows is installed, the device boots automatically using the same mode it was installed with.
To boot to UEFI or BIOS:
Open the firmware menus. You can use any of these methods:
Boot the PC, and press the manufacturer’s key to open the menus. Common keys used: Esc, Delete, F1, F2, F10, F11, or F12. On tablets, common buttons are Volume up or Volume down. During startup, there’s often a screen that mentions the key. If there’s not one, or if the screen goes by too fast to see it, check your manufacturer’s site.
Or, if Windows is already installed, from either the Sign on screen or the Start menu, select Power () > hold Shift while selecting Restart. Select Troubleshoot > Advanced options > UEFI Firmware settings.
From the firmware menus, boot to drive or network while in UEFI or BIOS mode:
On the boot device menu, select the command that identifies both the firmware mode and the device. For example, select UEFI: USB Drive or BIOS: Network/LAN.
You might see separate commands for the same device. For example, you might see UEFI USB Drive and BIOS USB Drive. Each command uses the same device and media, but boots the PC in a different firmware mode.
Some devices only support one mode (either UEFI or BIOS). Other devices will only allow you to boot to BIOS mode by manually disabling the UEFI security features. To disable the security features, go to Security > Secure Boot and disable the feature.
Some older PCs (Windows 7-era or earlier) support UEFI, but require you to browse to the boot file. From the firmware menus, look for the option: "Boot from file", then browse to \EFI\BOOT\BOOTX64.EFI on Windows PE or Windows Setup media.
Detecting UEFI or BIOS mode on a factory floor
Before installing Windows, check to make sure your firmware is booted to the right mode using any of these methods:
Use a script to check. Windows PE: create a script that checks which mode the device is booted in before installing. See WinPE: Boot in UEFI or legacy BIOS mode.
Use preformatted hard drives, and use a method that doesn't automatically format the drive. Use drives that have been preformatted using the GPT file format for UEFI mode, or the MBR file format for BIOS mode. When the installation starts, if the PC is booted to the wrong mode, Windows will fail to install, and the technician can restart the PC in the correct firmware mode.
Remove the UEFI or BIOS boot files: Windows PE or Windows Setup: remove the files that Windows PE or Windows Setup to boot in UEFI or BIOS mode. When the device is booted in the wrong mode, it will immediately fail to boot, and you can begin troubleshooting right away.
Boot only when in UEFI mode: Remove the bootmgr file from the root of the Windows PE or Windows Setup media. This prevents the device from starting in BIOS mode.
Boot only when in BIOS mode: Remove the efi folder from the root of the Windows PE or Windows Setup media. This prevents the device from starting in UEFI mode.