Deploying Windows to UEFI Firmware Overview

Applies To: Windows 8, Windows Server 2012

This topic discusses benefits, deployment considerations, and resources for installing Windows® 8 and Windows Server® 2012 on computers that use firmware that meets the Extensible Firmware Interface (EFI) and Unified Extensible Firmware Interface (UEFI) specifications.

Firmware is hardware-specific code that provides the first set of instructions that run during the boot process. After the firmware finishes detecting hardware and initializing the system, the firmware interface passes control to a boot application such as Windows.

UEFI is a replacement for the older BIOS firmware interface. UEFI specifications also replace the EFI 1.10 specifications, although the terms EFI and UEFI are often used synonymously.

Benefits of UEFI

Firmware that meets the UEFI 2.3.1 specifications provides the following benefits:

  • Ability to use security features such as Secure Boot and factory encrypted drives. For more information, see Secure Boot Overview and Factory Encrypted Drives.

  • Ability to boot from disks that are larger than 2 terabytes.

  • Faster boot and resume times.

Additional advantages are described in the Intel EFI and UEFI Overview and Specifications.

Before You Begin

Before you install Windows on a UEFI-based computer, note the following:

  • For some platforms, you may need to perform additional steps to make sure that Windows is installed in UEFI mode, and not in legacy BIOS-compatibility mode.

    For more information, see How to Switch from BIOS-Compatibility Mode to UEFI Mode.

  • UEFI hard disks require the GUID partition table (GPT) partition structure, instead of the master boot record (MBR) partition structure that is used in BIOS.

    When you install Windows by using the Windows product DVD, Windows Setup detects whether the computer was booted in UEFI mode or BIOS-compatibility mode, and it configures Windows based on this selection.

    For information about preconfiguring GPT partitions, see Hard Drives and Partitions Overview.

  • Windows® Preinstallation Environment (Windows PE) can be configured to support both UEFI mode and BIOS-compatibility mode.


    The version of the Windows PE boot files must match the computer architecture. An x64-based UEFI computer can boot by using only Windows PE x64 boot files. An x86-based computer can boot by using only Windows PE x86 boot files.

    For instructions, see Walkthrough: Install Windows PE to CD, USB Flash Drive, or USB Hard Drive or Walkthrough: Flat-Boot Windows PE.

  • Note to firmware manufacturers: Do not use tools or applications to alter Windows-specific boot files, including files in the C:\boot and C:\EFI folders. Altering these files could interfere with the computer’s ability to boot up, to resume from hibernation, or to run system recovery tools. Instead, use tools such as BCDboot to set the boot order. For more info, see BCDboot Command-Line Options.


UEFI specifications

Microsoft Hardware Developer Central: Firmware and Boot Environment

Intel EFI and UEFI Overview and Specifications

See Also


How to Switch from BIOS-Compatibility Mode to UEFI Mode


How to Configure UEFI/GPT-Based Hard Drive Partitions

Other Resources

UEFI Firmware
Unified Extensible Firmware Interface Forum (UEFI Forum)