Question Can someone explain how to make sure Windows 10 is set to GPT?

[t1redmonkey]

So I recently realised I can't fully utilise my graphics card (the Smart Access Memory) since my SSD is set to MBR for some reason. Even though I did a clean reinstall of Win 10 a few months ago. I don't even remember being asked during the install if I wanted it set to MBR or GPT when reinstalling.

My understanding is I basically need to do another reinstall of Win 10 now to convert it to GPT, however I can't really find any info on how to make sure it is reinstalled as GPT. Can someone give me clear instructions on how to ensure this is done please so I can have my SSD as GPT instead of MBR? Thanks.

 

[kerberos_20]

My understanding is I basically need to do another reinstall of Win 10 now to convert it to GPT, however I can't really find any info on how to make sure it is reinstalled as GPT.

you disable CSM mode in bios and then during installation it would tell you that windows cant be installed on this drive (as its MBR drive), deleting partitions and installing it on clean drive would make it GPT just fine

if you dont want to wipe your drive, then use mbr2gpt tool
info here https://www.windowscentral.com/how-convert-mbr-disk-gpt-move-bios-uefi-windows-10

 

[Lafong]

If you run Diskpart from the command line and then enter "list disk", you should see all of your drives. Probably named something like 0, 1, 2, etc.

At the right side of the list, all 3 of mine are shown as "gpt", with an asterisk.

 

[t1redmonkey]

you disable CSM mode in bios and then during installation it would tell you that windows cant be installed on this drive (as its MBR drive), deleting partitions and installing it on clean drive would make it GPT just fine

if you dont want to wipe your drive, then use mbr2gpt tool
info here https://www.windowscentral.com/how-convert-mbr-disk-gpt-move-bios-uefi-windows-10

Thanks for the link. Under the section titled 'Convert MBR to GPT partition style (offline)' will that convert the whole SSD to GPT without deleting any data if I follow that method?

 

[SkyNetRising]

how to make sure Windows 10 is set to GPT?

Open Disk Management, right-click on disk, choose properties/volumes and check partition style.

4 Quick Ways to Check Partition Style on Windows 11

Check your SSD partitions so you know how to deal with issues if they appear.

www.makeuseof.com

My understanding is I basically need to do another reinstall of Win 10 now to convert it to GPT,

No. You don't need to reinstall.
You can use mbr2gpt tool to convert OS drive from MBR to GPT.

Note - your motherboard has to support UEFI boot.
If it doesn't, then after conversion your pc becomes unbootable.

 

[t1redmonkey]

you disable CSM mode in bios and then during installation it would tell you that windows cant be installed on this drive (as its MBR drive), deleting partitions and installing it on clean drive would make it GPT just fine

if you dont want to wipe your drive, then use mbr2gpt tool
info here https://www.windowscentral.com/how-convert-mbr-disk-gpt-move-bios-uefi-windows-10

So for some reason, when following the method under 'Convert MBR to GPT partition style (offline)', after I get to step 6 my options do not match the screenshot - I literally only have one option appearing: Startup settings. Whereas the screenshot indicates there should be 6 options.

 

[kerberos_20]

So for some reason, when following the method under 'Convert MBR to GPT partition style (offline)', after I get to step 6 my options do not match the screenshot - I literally only have one option appearing: Startup settings. Whereas the screenshot indicates there should be 6 options.

no recovery options? odd, but you can get those when you insert windows install media on usb stick, then use troubleshoot/repair option there instead of installation, that should get you to same options as seen on that guide

 

[t1redmonkey]

no recovery options? odd, but you can get those when you insert windows install media on usb stick, then use troubleshoot/repair option there instead of installation, that should get you to same options as seen on that guide

Well that worked, but the next steps failed. Couldn't validate the drive, and even when I specified the drive the OS was installed on, it said it couldn't find the OS partition for some reason

https://imgur.com/a/u3hvcA9

View: https://imgur.com/a/u3hvcA9

 

[t1redmonkey]

Well I can say with a lot of relief I managed to get it converted to GPT! But had to do a load of other things...I will document them in case anyone comes across this in the future:

In an elevated command prompt:

bcdboot C:\Windows /s C:

Also the partition wasn't marked as active in Disk Management so I did that too.

Then repeated the commands in my previous screenshot and was able to convert it.

However, I then couldn't boot into Windows 10 after the conversion, initially I got to the log in screen then I got some corrupted blue screen of death screen, and after that I couldn't even load into the log in screen, PC just kept restarting over and over.

I then had to boot from a USB recovery drive and do the following commands in CMD (which I found from another forum thread):

diskpart
list disk (take note of your drive number n)
select disk n (change n with the drive number you found above)
list part (It will list all the drive partitions. Take note of your System partition number x )
select part x (change x with the System partition number you found above)
format fs=fat32 label=EFI quick
assign letter t
list vol (make sure Windows is C: and EFI is T
exit (to exit diskpart)
bcdboot C:\Windows /s T: /f UEFI (it will create a boot manager that takes the boot sequence to C
exit

Then it finally worked and now I'm back in Windows and with a GPT drive

https://imgur.com/IOvKgjd

View: https://imgur.com/IOvKgjd