Convert Windows 10 from Legacy BIOS to UEFI without Data Loss  

Brink said:

Did you make the "C:" drive active first?

If so, you could try the startup repair without the other disks connected.

Yea, no, I kept unplugging all of the wrong drives because I thought my m.2 drive was my boot drive, so now that I know it isn't, I have to do a complete wipe and reinstall onto the m.2 drive. Well....I guess I don't have to wipe the drive....is there a way for me to reformat and set up my m.2 drive (disk 3 in the original picture) to be uefi and then transfer over my windows install somehow without having to wipe the drive that was my windows drive?

deadlyvortex said:

Yea, no, I kept unplugging all of the wrong drives because I thought my m.2 drive was my boot drive, so now that I know it isn't, I have to do a complete wipe and reinstall onto the m.2 drive. Well....I guess I don't have to wipe the drive....is there a way for me to reformat and set up my m.2 drive (disk 3 in the original picture) to be uefi and then transfer over my windows install somehow without having to wipe the drive that was my windows drive?

If the m.2 is like one of these shown here it is not easily "unpluggable", have to remove a screw to enable it being removed.
m.2 drive at DuckDuckGo
I would think being more securely fastened to the motherboard it should be seen as Disk 0 in the BIOS.

Berton said:

If the m.2 is like one of these shown here it is not easily "unpluggable", have to remove a screw to enable it being removed.
m.2 drive at DuckDuckGo
I would think being more securely fastened to the motherboard it should be seen as Disk 0 in the BIOS.

That was my assumption as well, but nonetheless, when i click on disc 3, and go to properties, it reveals itself as my 960 evo. My mushkin eco ssd is disk 0 for some strange reason.

Brink said:

deadlyvortex,

If you like, you could try this below to avoid a clean install:

When you have all disks disconnected other than the M.2, check to make sure the M.2 is selected as your boot drive in your BIOS, and see if a startup repair can repair the boot manager to allow you to boot from the M.2.

When I disconnect all of the other drives, it can't boot because there are no boot files or system files on teh m.2 drive. I originally botched my windows installation and installed everything on the wrong drive

The good news is that I can make sure I do it right and with uefi this time though. Thanks for helping me discover the error I made though Brink, I appreciate it!

I've browsed this thread for information about converting basic disk to GPT and seemingly it would work on my laptop.

Both the "mbr2gpt validate /allowFullOS" and the " reagentc /info" show no issues.


The laptop has a single drive:



My question is, once the the drive had been converted, is there a way to reverse the process?

TIA...

@Cr00zng,

Why do you want to convert the drive to GPT?

Yes, you can reverse the process, but it requires an external drive to do so. You would have to create a backup image of the internal drive saved to the external drive with a program such as Macrium Reflect Free. Then you re-initialize the internal drive back to MBR, and restore the backup image to it.

If you only want to enable UEFI booting, you can do that without converting the drive to GPT. You only have to recreate the System Reserved partition as a FAT32 system partition, and recreate the boot files in it.

NavyLCDR said:

@Cr00zng,

Why do you want to convert the drive to GPT?

Yes, you can reverse the process, but it requires an external drive to do so. You would have to create a backup image of the internal drive saved to the external drive with a program such as Macrium Reflect Free. Then you re-initialize the internal drive back to MBR, and restore the backup image to it.

If you only want to enable UEFI booting, you can do that without converting the drive to GPT. You only have to recreate the System Reserved partition as a FAT32 system partition, and recreate the boot files in it.

Thanks NavyLCDR...

The reason for the conversion is to set up Bitlocker with the Samsung SSD 850 EVO, utilizing the drives hardware encryption (SED), instead of the Bitlocker software encryption. The MBR to GTP is one of the hurdle in this process, but still learning. The other is to change the BIOS to EUFI boot only; the order of making these changes is important; I learned it on the hard way...

Recreating just the "System Reserved partition as a FAT32 system partition" seems like a neat trick, but may cause issues with Bitlocker...

Yes, the system is backed up via Macrium image, I would not do these kind of experiments on a system without creating a new image. Even, if the system in question is rather old, Thinkpad T430, and not that important...