UEFI installation on non-UEFI system


  1. Posts : 95
    Windows 10 Pro
       #1

    UEFI installation on non-UEFI system


    Hi there,
    I wanted to boot an existing Windows 10 install taken from a UEFI notebook into an older non-UEFI notebook and I only get a flashing cursor. Booted with an installation media and the automatic startup repair did not work.
    Browsing online I tried re-creating the boot sector but in the end I understand that to do so I need to attempt the fix from a UEFI system.

    I perfectly understand that a Windows installation should not be moved to a different system but I was hoping to manage to boot it up to save some files. Alternatively, I can plug the HDD into another PC.

    Is there anybody aware of a way to make this installation work?
    Thanks
    Tony
      My Computer


  2. Posts : 17,281
    Windows 11 Pro
       #2

    The main problem is that you will have to convert the drive from GPT style partitioning to MBR partitioning so that you can mark a partition as active to be able to boot from it in legacy BIOS. The easiest way to do that is to create an image of your Windows and any data partitions using a program like Macrium Reflect Free, then convert the drive to MBR, then restore the partitions back and create your boot files required to boot in legacy mode.

    Alternatively, you can copy the partitions to a second HDD/SSD partitioned as MBR, create the boot files on it, and then install that in the legacy BIOS computer.
      My Computer


  3. Posts : 13,587
    Windows10
       #3

    NavyLCDR said:
    The main problem is that you will have to convert the drive from GPT style partitioning to MBR partitioning so that you can mark a partition as active to be able to boot from it in legacy BIOS. The easiest way to do that is to create an image of your Windows and any data partitions using a program like Macrium Reflect Free, then convert the drive to MBR, then restore the partitions back and create your boot files required to boot in legacy mode.

    Alternatively, you can copy the partitions to a second HDD/SSD partitioned as MBR, create the boot files on it, and then install that in the legacy BIOS computer.
    Maybe a slightly easier way to do this for a beginner (creating boot files is slightly tricky) is

    1) backup c drive partition (recommending Macrium Reflect Free of course)

    2) use MS media creation tool and install Windows 10 on PC (may need to convert drive to mbr first)

    3) Restore C drive partition image over new C drive.


    It's a pity we do not have the reverse tool of mbr2gpt i.e. gpt2mbr to make conversion dead easy.
      My Computer


  4. Posts : 95
    Windows 10 Pro
    Thread Starter
       #4

    Thanks, that's what I was looking for. I'll educate myself on the difference between EUFI/non EUFI, GPT/MBR!
      My Computer


  5. Posts : 12,430
    Win10 Version 21H2 Pro and Home, Win11 Pro
       #5

    One way I've done it with older computers is to boot to a GPARTED CD, delete all partitions to give the drive an as-shipped condition then boot to the version of Windows desired and install, seems to take care of the problems encountered when trying to change an existing condition. It has worked with both 32-bit and 64-bit versions.
      My Computers


  6. Posts : 13,587
    Windows10
       #6

    OP is not wanting to clean install.

    No need to use gparted really.

    Just boot from usb drive installation drive, press shift+f10 to get to command prompt and run diskpart to wipe drive.
      My Computer


  7. Posts : 17,281
    Windows 11 Pro
       #7

    cereberus said:
    OP is not wanting to clean install.

    No need to use gparted really.

    Just boot from usb drive installation drive, press shift+f10 to get to command prompt and run diskpart to wipe drive.
    or just go to the custom install option and on the next screen delete all the existing partitions - but I don't know if that would allow Windows 10 to install in legacy BIOS (MBR) mode like diskpart would.

    diskpart
    select disk 0
    clean <-This erases the ENTIRE drive!
    exit
    exit
      My Computer


  8. Posts : 12,430
    Win10 Version 21H2 Pro and Home, Win11 Pro
       #8

    I only recommend GPARTED as there are times when Windows won't allow what is desired, one of the times is in changing from 32-bit to 64-bit or 64-bit to 32-bit and the other has been when changing a drive to fit what the BIOS allows.
      My Computers


  9. Posts : 13,587
    Windows10
       #9

    op
    NavyLCDR said:
    or just go to the custom install option and on the next screen delete all the existing partitions - but I don't know if that would allow Windows 10 to install in legacy BIOS (MBR) mode like diskpart would.

    diskpart
    select disk 0
    clean <-This erases the ENTIRE drive!
    exit
    exit
    You may need to add "convert mbr" after clean.
      My Computer


 

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