BIOS mode as Legacy or UEFI?

My Windows 10 says its BIOS mode is Legacy with C drive partition as MBR. Is it worth switching to UEFI mode with C drive as GPT partition? Why does it seem so difficult to install to UEFI mode with GPT partition? You do not get an option to choose when you install windows 10 on a clean disk with Windows 10 USB installer tool. I never really thought of this when installing windows 10. I thought it would automatically go UEFI. Do most people not care about this?

It is also annoying that Window's 10 backup create image does not work and I think it is related to your BIOS mode and partition. I can't install a backup image of my current windows 10 without getting an error message.

Windows 10 will install itself in the same mode that the installation media is booted in. If you boot the installation media in legacy BIOS (CSM) mode, then Windows 10 will create an MBR partitioned drive and install in legacy BIOS (CSM) mode. If the installation media is booted in UEFI mode, Windows 10 will create a GPT partitioned drive and install in UEFI mode.

Whether or not you want to convert your MBR install to GPT, and whether or not you want to convert your legacy BIOS (CSM) mode booting to boot in UEFI mode , or if you want to reinstall in UEFI mode is up to you. What do you hope to gain? Side note: converting the drive from MBR to GPT is not required to convert to UEFI booting. However converting to UEFI booting is required if you want to convert the drive to GPT.

What error are you getting when you try to restore your backup image, and what backup software are you using?

Hi folks
Easy way to convert Windows drive to GPT without re-installing Windows or losing data.

1) in Diskpart convert GPT.

2) use a partition manager to create an efi partition -- say size=100mb. You might have to slightly shrink the current OS "C" partition to create space for this -- any decent partition manager can re-size and move partitions without any problems these days.

3) boot stand alone Macrium and select fix boot problems.


Job done -- now Windows on GPT drive and will boot uefi -- no re-install etc necessary.

Cheers
jimbo

@jimbo45,

The convert GPT command in diskpart will only work on a clean drive. It will not work if the are partitions on the drive. It is not a method that can be used without first deleting everything off the drive. In diskpart, run "help convert gpt" and read the returned text.

NavyLCDR said:

@jimbo45,

The convert GPT command in diskpart will only work on a clean drive. It will not work if the are partitions on the drive. It is not a method that can be used without first deleting everything off the drive. In diskpart, run "help convert gpt" and read the returned text.

Hi there

@NavyLCDR

Thanks for the correction.

I forgot about that -- however it's still possible with an addition of a couple of extra steps -- backup existing HDD first then create partitions on HDD of appropriate sizes and convert, restore and do the fix windows boot problems.

It's worth doing this way rather than re-installing as you will then have a backup !! and probably safer (and quicker) than trying to install everything again from scratch on a totally new version of Windows.

I think my brain is a bit addled today back home again after all that Wimbledon Tennis when I was in London last week with Strawberries and Champagne !!!!! and of course English famous warm beer !!! at Wimbledon's really fun Dog and Fox pub and numerous other "Watering Holes" !!!!!

Cheers
jimbo

Again, though, it is not required to convert the drive to GPT just to boot in UEFI mode.

x509 said:

Jimbo,

Cheers and I hope you have been enjoying all that Tennis.

So let me restate what you have said here.

1. Use Macrium Reflect to back up the existing HDD partitions. Defragment each partition to minimize the space actually needed for each partition when doing the restore operation. (In my case I have an MBR drive with three non-production Win 10 partitions, so I would need to run Macrium separately for each partition.)

2. Run diskpart and then convert GPT.

3. Use a partition manager, in my case MiniTool Partition Wizard to create an efi partition -- say size=100mb.

4. Use MiniTool to create new partitions that are the same size or slightly smaller.

5. Boot Macrium from a USB drive to restore each partition.

6. Enjoy!

1. You do not need to defragment. If you change the partition size of the target partition from the original partition even slightly, then Macrium will restore file by file and you will end up with a defragmented target partition. Also, you don't need to do a separate backup of each partition. One single image containing all of the partitions is all that is required.

2. You will need to run:
diskpart
list disk
select disk #<- replace # with the actual # of the drive you want to convert
clean<- This will erase the drive selected above, make sure you selected the correct drive!
convert GPT

3. After the convert GPT command, just create the partition in diskpart:
create part EFI size=100
format fs=FAT32 quick
assign letter=t
exit

4. I'm not sure you need to use MiniTool Partition Wizard to create anything.

5. Restoring individual partitions from your images is a drag and drop operation. I believe you drag the desired partition to the unallocated space on the target drive. Change the partition size, even slightly, and the new partition will be defragmented when Macrium restores it.

6. You will need to establish boot files in the new EFI partition you created. The command line command is:
bcdboot C:\Windows /s T: /f all

You need to run the bcdboot command for each Windows 10 partition you restore, and change the drive letter C: to match whatever drive letter the restored partitions get. The drive letter T: corresponds to the drive letter you assigned to the EFI system partition in the diskpart commands.