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I have a laptop that has Windows 7 64 bit Enterprise edition. It is already filled with plenty of Software and drivers.

The laptop (Dell E6220) supports booting through UEFI, but the insatllition was on legacy BIOS.

When I try to change the booting from Legacy to UEFI I get an error message that no boot device was found (the Windows 7 doesn't recognize as bootable). Is there any way I can configure the current install to allow booting from UEFI or do I have to format and reinstall?

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2 Answers 2

up vote 4 down vote accepted

Windows 7 on UEFI requires that the disk partitions use GUID partition table (GPT) rather than the traditional MBR partitioning format found on BIOS systems. Unfortunately, windows provides no way of converting an MBR partition to a GPT one non-destructively. However, if you don't mind copying data off your drive, converting, then copying it back then you could use windows to do it as described here.

If you don't want to backup the data first and have access to a a linux machine that you can install the drive in, there are tools in linux that will allow you to convert the partition type non-destructively as described here. If you don't have a linux box handy, you can also try creating a linux boot CD and booting from that.

Searhing for "convert MBR to GPT" brings up other tools, but I have never tried them.

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Hi zdan; can you expand on your answer by including the relevant information here? It seems very much like a Google search, not an answer, in its current form. Thanks! –  Canadian Luke Sep 15 at 19:45

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][1]
       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][2]
       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:
       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:
       mkdir b:\EFI
       mkdir b:\EFI\Microsoft
       cd /d b:\EFI\Microsoft
       bootrec /fixboot
       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.

Proof: How to Convert Windows 7/8/8.1 Installation from Legacy to UEFI Without Data Loss!

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your good link: www.youtube.com/watch?v=Qk6_K9hVu_k –  Remus Rigo Sep 15 at 17:09
Thanks, I have updated it in the answer. –  Nehal J. Wani Sep 15 at 19:41

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