- Create a system repair disc (http://windows.microsoft.com/en-US/windows7/Create-a-system-repair-disc ). You can skip this step if you have a Windows installation media. Is a good measure to reboot and verify you can start your system from this disc.
- Identify which disk you want to convert (usually is #0). This can be done by looking at the number in the Windows Disk Management.
- Download gptgen from here http://sourceforge.net/projects/gptgen . (You could use the Windows Disk Management Tool for this too. (diskmgmt.msc)) This tool will allow you to convert your MBR disc to GPT with the data included.
- ATTENTION: After this step, your computer CANNOT BOOT until the whole process is completed. DO NOT Shut Down Unless Instructed to!
Unzip gptgen and then run CMD with elevated privileges. (replace the 0 with the identified disk number).
This *will* result in a BSOD shortly after and it’s to be expected:
gptgen.exe -w \\.\physicaldrive0 - Boot using your Windows installation or previously generated system repair disc.
- Choose language and preferences, and then select Repair Your Computer -> Troubleshoot -> Advanced options -> Command Prompt
- We will need the disk partitioning tool. With this, we will recreate the boot partitions. Type:
diskpart - Identify the boot disk where Windows is located, typing:
list diskSomething like this should appear:
Disk ### Status Size Free Dyn Gpt-------- ------------- ------- ------- --- ---* Disk 0 Online 128 GB 0 B * - Once identified, select the disk (replace with the correct number):
select disk 0 - Verify the partitions:
list partition - Something similar at the info below should appear.
Partition ### Type Size Offset------------- ---------------- ------- -------Partition 1 Primary 350 MB 1024 KBPartition 2 Primary 126 GB 350 MB - Delete the previous system partition:
select partition 1delete partition - Create the new boot partition, Microsoft reserved partition:
create partition EFI size=100 offset=1format quick fs=fat32 label="System"assign letter=Screate partition msr size=128 offset=103424 - If you list the partitions again, you should have ended up with something like this:
Partition ### Type Size Offset------------- ---------------- ------- -------Partition 1 System 100 MB 1024 KBPartition 2 Reserved 128 MB 101 MBPartition 3 Primary 126 GB 229 MB - Ensure that your Windows installation is mounted, replacing 3 with the volume number of the Windows installation (usually 1):
list volumeselect volume 3assign letter=C - Exit diskpart:
exit - Generate boot partition data, replacing C: with the letter of the Windows installation (usually C:):
bcdboot c:\windows /s s: /f UEFI - Cross your fingers and then
restart your computer!
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