Convert MBR to GPT

Discussion in 'Windows 10' started by Mr Been, Feb 4, 2019.

  1. Mr Been

    Mr Been MDL Senior Member

    Feb 24, 2008
    I want to change booting and installing Win10 from MBR to GPT.
    I install Win10 always "UNATTENDED" and before installation I format the disk onto Win10 will be installed to NTFS-filesystem.
    Or do I have to change to FAT32, or are both filesystems allowed?
    And all the other additional installed disks, have they to be converted to GPT too, if they are not bootable?
    If I re-format this bootable GPT-disk, will this one stay a GPT-disk?
    Then I have to change in BIOS the Option "CSM-Support" ==> DISABLED

    A step by step would be very helpful.

    Thank you for helping
  2. Enthousiast

    Enthousiast MDL Tester

    Oct 30, 2009
    When you now are running a MBR partitioned system and want to switch at reinstall to GPT (UEFI), you only need to delete all existing partitions from the system drive (and have no other drive connected) and repartition it when booted from UEFI capable boot media (DVD or FAT32 formatted USB drive (or use a third party usb creator, like Rufus)) and it will install in GPT.

    You can have CSM enabled or disabled, when the bootmedia with the UEFI suffix is selected during boot, it should install UEFI/GPT.

    You also can convert the existing MBR partitions to GPT, using diskpart and the needed commands.

    I never use unattended xml's, can't help with that.
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  3. endbase

    endbase MDL Guru

    Aug 12, 2012
    about converting a MBR disk to GPT a friends computer could not upgrade any more because of the disk being MBR had to convert it to GPT for the upgrade to take place. I had to clean the disk in diskpart for the conversion to take place after that I had put back a backup and voila it worked. Stupid enough after reading on the net you should convert MBR to GPT with keeping the files but all I got where errors in diskpart untill I used clean that figures

    Just a note on the subject
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