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Convert MBR To GPT, Drive Does Not Boot

wexmarywexmary
edited February 2015 in AOMEI Products Support

Partition Assistant.

 

I have a 4-year old MBR hard drive Win 7 Pro x64 from a Dell XPS 9000, the CPU died but drive is good.  I need to use it on another CPU because of apps that I have no disks for.  I know there may be driver issues but I can deal with those.

 

I cloned drive to a backup.  I have an Optiplex 990 at work, drive boots and works in Legacy mode after a couple of driver additions.

 

Everyone tells me that in order to use that drive in a new CPU (Dell XPS 8700, or Dell Precision 5620), I have to do diskpart, clean and then reinstall Win7.  But then I lose my apps.

 

I tried converting my old hard drive to GPT with Partition Assistant.  It seemingly converts.  But after changing BIOS to UEFI, it does not boot.  There is no boot device selected and I am given a prompt to manually add a boot device in UEFI.  it is not like MBR where you can select your boot devices.  I have no idea how to manually add a device.

 

So I try to convert back to MBR, and even though your software says it is an MBR drive, BIOS sees it as a UEFI disk.  But it boots from neither.

 

What am I doing wrong?

 

Thanks

 

Comments

  • YoungChengYoungCheng

    Hi wexmary,


    You used the free version or paid version of Partition Assitant? If you use the free version, it cannot boot after converting. If you used the paid version, what error message was when you boot from the disk? So we can analyze what caused the problem. 

  • RootmanRootman
    edited February 2015

    Wexmary, MBR (legacy) boot and UEFI boot are two entirely different animals and require totally different disk schemes. 


    If your original system was MBR (legacy) it must remain MBR (legacy) and while the disk can be converted to GPT it will not - as you've found out - boot as it should.  If your original system was UEFI then it must be moved to a new disk as UEFI.  If the original boot setup was MBR (legacy) - which a Windows 64 bit OS certainly can be - you can't just convert the disk to GPT and make it work.


    The one place you CAN use a GPT disk on a system that boots to MBR is as a second data drive, and this is only of any use if the second data drive exceeds 2TB in size, and you want any single partition to be larger than 2TB, otherwise a standard MBR disk setup is just fine.


    UEFI requires the disk be marked as GPT and that the proper EFI boot files
    be in a smallish FAT 32 primary parition that is at the front of the drive.  The rest of the OS is placed on an NTFS primary parition.  Most systems have a few other primary paritions that the computer manufacturer  may have setup for restoration or utiity use.

       
              

  • jmdjmd
    Here is how you do it. Use AOME Pro (not the free version). Convert the entire disk to MBR.   Reset your BIOS to legacy boot. Boot to a recovery disk. and go to troubleshoot. Select advanced options, command prompt. At the X prompt, type bootrec /fixmbr and click enter. Type bootrec /fixboot and click enter. (you may get a system not found).  (One of my employees stated he also needed to enter the bootrec commands again at the OS prompt, usually C:). Restart again and boot to the recovery disk. This time select "startup repair". When that finishes it should boot normally. This has worked 3 times for us.      
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