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Lost boot after MBR to GPT conversion

cashino Posted messages 40 Status Member -  
cashino Posted messages 40 Status Member -

Hello,

I cloned my HDD to an SSD using Aomei Backupper, checking the box to clone to an SSD, and then I successfully booted with the SSD. However, I took the opportunity to convert the original MBR partition table to GPT with Aomei Partition Assistant, making sure to enable "AHCI and UEFI boot" in the BIOS of my Asus G73s from late 2011. After that, I ended up with a black screen and a cursor in the top left corner, and no booting. I re-cloned it in MBR and it works again, but I would like to understand why this happens?

This isn't the first time on old machines that the conversion to GPT doesn't work even though the AHCI/UEFI options are available...

3 answers

  1.
    fabul Posted messages 42158 Registration date   Status Moderator Last intervention   6 066
     

    Hello,

    To convert an MBR system disk to GPT, you can use MBR2GPT

    A very short summary, but easy to follow

    Settings
    Update and Security
    Recovery
    Restart

    In Recovery Mode
    Troubleshoot
    Command Prompt

    mbr2gpt /validate
    mbr2gpt /convert

    After that, you will need to switch your BIOS to UEFI to be able to boot

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    1. cashino Posted messages 40 Status Member 2
       

      without formatting it? because Aomei Partition Assistant has already managed to do this many times without needing to format

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      1. fabul Posted messages 42158 Registration date   Status Moderator Last intervention   6 066 > cashino Posted messages 40 Status Member
         

        No formatting.

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  2. flo88 Posted messages 28490 Registration date   Status Contributor Last intervention   Ambassadeur 5 169
     

    Hello

    For the GPT and UEFI conversion to be valid for a boot disk, the motherboard's BIOS must be in native UEFI, which I highly doubt for a laptop from 2011.

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    1. cashino Posted messages 40 Status Member 2
       

      Native? Does that mean that even if there is the UEFI option in the boot section of the BIOS, the PC cannot boot? But then why have this option?

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      1. flo88 Posted messages 28490 Registration date   Status Contributor Last intervention   5 169 > cashino Posted messages 40 Status Member
         

        UEFI is only native if it displays " BIOS Legacy (legacy) " in the available BIOS choices. In this case, UEFI "emulates" the old BIOS in a way.

        Depending on the BIOS, the "legacy" line may be written as "CSM"; it's the same, by convention. There were native UEFIs in 2011, but not many...

        Also, be careful with AOEMI; it has done strange things with GPT disks for me.

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  3. cashino Posted messages 40 Status Member 2
     

    My SSD is the CT (Crucial). According to what you said, I have the impression that it's not a native UEFI.. I haven't tried with mbr2gpt yet, I'll test it tonight!

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