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Convert a Legacy BIOS SSD to UEFI

Forum Member
Posts: 6
Comments: 32

I reinstalled W8/8.1 on a 120GB SSD and somehow ended up with a Legacy BIOS installation (2 Partitions 350MB System Reserved and a 111.45GB System Boot Partition). The MB I'm using supports UEFI. Is there a procedure documented somewhere explaining how to use Acronis TI 2014 to convert the SSD to the GPT format that will support the UEFI BIOS implementation? I know I can go back to square one and try to do a fresh reinstall W8/8.1 in the correct format but I have invested hours in setting up W8/8.1 and would like to avoid starting over.

Forum Hero
Posts: 34
Comments: 6885

This link might help.

http://www.disk-partition.com/gpt-mbr/convert-mbr-to-gpt-without-data-loss.html

Forum Hero
Posts: 82
Comments: 9176

I am wondering whether this tool work for a boot disk though...
In case it doesn't, here is what I would do;
- do a full disk backup of the SSD in its MBR config,
- disconnect the computer from the internet (this will avoid that the installer donwloads a bunch of updates, and avoids the early activation of Windows)
- install windows on the new SSD, asking the installer to reformat the disk and set it up as GPT
- restore the C:\ partition of your backup onto the freshly installed partition
- try to boot. You might have to use the installation disk to repair the computer startup
- connect the computer to the internet; verify the activation is working, and that the computer works normally (windows updates, etc.)

Forum Hero
Posts: 34
Comments: 6885

Good point Pat, I have not used the tool to do as you say a boot disk so I cannot say for certain that it would work as intended.

Forum Member
Posts: 6
Comments: 32

Pat L,
I was on my way to trying what you suggested but then I discovered a couple of other strange things going on with the W8.1 "MBR" system so I bit the bullet an spent several hours reinstalling. This time I did it right and set it up in the GPT format. All seems to be OK.

Bob,
I did download the free version of AOMEI Partition Assistant and plan to play with it on a non-boot hard drive. If it works as advertised I'll probably spring for the Pro version and give it a try. With all the trouble I've had getting three systems to run W8.1 I think I'll buy a spare SSD to play with! I also need to build some confidence using TI 2014/W8.1/GPT without risking the loss of a system. TI 2010 was great for W7 and never left me down.

Thanks all for the link and suggestions.

Beginner
Posts: 0
Comments: 1

Working Proof: https://www.youtube.com/watch?v=Qk6_K9hVu_k

Convert Windows Installation from Legacy to UEFI:

Please note that this technique will work only for those computer systems which support UEFI firmware. Please check
that first in your BIOS settings and then continue with this tutorial.

Step1: Confirm that you installation is indeed in Legacy Mode. Press WinKey + R and then type msinfo32 and hit enter.
The BIOS mode should be Legacy in System Summary.

Step2: Download System Rescue Disk and make a bootable media from it.
Download the disk from: http://www.sysresccd.org/Download
Instructions to make bootable media: http://www.sysresccd.org/Sysresccd-manual-en_How_to_install_SystemRescueCd_on_an_USB-stick#B.29_Recommended_USB_installation_method_from_Windows
That is pretty trivial and I won't be covering it in this tutorial.

Step3: Reboot into Legacy or UEFI mode using the bootable media that you created in Step2.

Step4: Run the command: testdisk
Use the arrow keys to navigate.
Select your HDD in which Windows is installed in Legacy Mode and press enter.
Select [EFI GPT] EFI GPT Partition Map and press enter.
Select Analyze and hit enter.
Select Quick Search (at the bottom) and hit enter.
Select Continue (at the bottom) and hit enter.
Hit enter again.
Select Write (at the bottom) and hit enter.
Press Y and hit enter.
Your partition table has changed from MBR to GPT.

Step5: Reboot into UEFI mode using Windows recovery/installation media.

Step6: Open command prompt. Shortcut is: shift+F10

Step7: Run the following commands:
diskpart
list disk :Note the disk number which contains your windows installation. Let us say, it is x
select disk x
list partition :Note the partition number which contains your windows installation. Let us say, it is y
select partition y
shrink minimum=200 desired=200
create partition efi
list partition :Note the partition number of the new one. Let us say, it is z
select partition z
format fs = fat32
assign letter = b:
exit
mkdir b:\EFI
mkdir b:\EFI\Microsoft
cd /d b:\EFI\Microsoft
bootrec /fixboot
diskpart
list vol
bcdboot c:\windows /l en-us /s b: /f ALL
Please note that here c: denotes the letter of the partition in which windows is installed. Lets find that out first.

Step8: Reboot. Tada! Done! Check whether your installation has changed into UEFI or not.

Forum Hero
Posts: 34
Comments: 6885

Very clever, learn something new every day!

Forum Member
Posts: 1
Comments: 93

Claims to show this, but the author of the video is using win10 which doesn't actually prooveno data loss, because a clean install of win10  will be uefi boot by default  certainly if from usb stick  I have a win 7 system disk , installed on a skylake system so fully supports UEFI boot, but because i installed win 7 using DVD installation media  in part due to there being no usb3 support in win 7 so usb doesn't work during install (even usb 2 ports )

My conumdrum is that i want to install this existing win7 system onto a new larger NVME ssd and make use of the M2 slot on the motherboard, i have zero intentions of down grading to win 10 i purchased ATI 2018 because i belived that this software was capable of doing this, i don't wish to be messing around with cmd prompts