Windows 8 and 8.1 Forums

Use legacy boot mode in Windows 8.1

  1. #1

    Posts : 61
    Windows 8.1 Pro, Windows 7 Professional

    Use legacy boot mode in Windows 8.1

    I've been wondering if it's possible to use the legacy (Windows 7 and earlier) BIOS instead of UEFI in Windows 8.1. In my BIOS settings, there is an option to enable the legacy boot mode, but Windows won't boot whenever this is enabled (I get the message 'Operating System not found' instead). Is there any way to enable this?

    NOTE: I am not talking about secure boot; I already have that disabled.

    Thanks in advance.

      My System SpecsSystem Spec

  2. #2

    Posts : 61
    Windows 8.1 Pro, Windows 7 Professional

    Also, I'm using a Dell Inspiron 15 laptop in case that matters.
      My System SpecsSystem Spec

  3. #3

    Posts : 5,357
    7/8/ubuntu/Linux Deepin

    It is a Windows weirdness. It won't boot from a gpt partition unless you use efi.

    If you want to use Bios, windows needs to be on an mbr partitioned disk.
      My System SpecsSystem Spec

  4. #4

    Posts : 5,357
    7/8/ubuntu/Linux Deepin

    GPT>MBR is doable. Various partition mangers will do it.

    You also need a primary partition marked active ( that can be the windows partition , separate one not required).
      My System SpecsSystem Spec

  5. #5

    Posts : 65
      My System SpecsSystem Spec

  6. #6

    Posts : 111
    Windows 8.1 Pro with Media Center

    Yes, you will have to turn on CSM "Compatibility Support Module" in the bios, however, Windows 8 is optimized to run more efficient in UEFI mode.

    When you try to install Windows 8, did you delete all the partitions, then click new? Windows will create the necessary partitions on the hard drive. The partitions are needed to boot in a UEFI environment.

    Partitions are as followed

    MSR Reserved

    Install to the primary drive.

    Plus you need secure boot on with Windows 8 installation.
      My System SpecsSystem Spec

  7. #7

    Posts : 148
    Windows 8.1 Update 1

    If Windows is installed in UEFI mode it definitely won't boot in legacy mode. It's not possible since under UEFI Windows uses a different type of bootloader. That's why it won't boot when legacy mode is enabled. The bios simply does not find the bootloader where it expects it.

    If you want to run Windows in legacy mode you will have to reinstall Windows by booting the setup DVD in legacy mode.

    Converting GPT to MBR partitions is possible though, just search the web for a program that can do it, there are a few out there. But make a backup of your important data before you try to convert your partitions.
      My System SpecsSystem Spec

Use legacy boot mode in Windows 8.1

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