Windows 8 and 8.1 Forums


Switching to UEFI from Legacy post Windows 8.1 install

  1. #1


    Posts : 4
    Windows 8.1

    Switching to UEFI from Legacy post Windows 8.1 install


    Hi folks I'm new to the forum and pretty much new to forums in general so I do apologize in advance for being a noob and any potential mistakes I make.

    I recently bought a used laptop (Dell 7720) I did a complete fresh install of windows 8.1, including drivers, applications etc. I cloned my HDD to a SSD and now am booting from that and using the HDD as a mass storage.

    Since the install I have realized my system is set to boot in Legacy mode but I have recently read there are various benefits from booting in UEFI mode. So what I'm wondering is if the difference is worth making the change and if so what do I need to do to enable UEFI mode?

    I understand how to switch from UEFI in the bios but there are other options like boot order etc.

    I'm also wondering if I'd be required to re-install and start fresh or if it's as simple as switching modes. Would switching modes create some sort of driver conflict or application conflict ,etc.?

    If it's really not worth the switch I'd just as soon leave it alone.

    I hope that's enough info to go on and I do appreciate any help. Thanks in advance.

      My System SpecsSystem Spec

  2. #2


    My own experience is that if your boot drive is MBR partitioned, and you switch your bios to UEFI mode, you will not be able to boot your OS. You will end up in the UEFI shell instead.

    It is conceivable that your OS actually is on a GPT partitioned drive, and your bios is operating in legacy mode anyhow. If you check the Disk Management utility (can find by typing it in windows search bar), you should see at least 4 partitions on your boot drive if it is GPT partitioned (more if you added any yourself). In that case, you only have to switch bios mode to get all UEFI goodness.

    If your drive is MBR partitioned, you will probably need to re-install. There are some utilities out there that claim to convert everything from MBR to GPT, but I do not know if they work at all, and I especially don't know if you can use one while your OS is on the drive you are trying to convert.
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  3. #3


    Posts : 4
    Windows 8.1


    OK well, my drive is definitely MBR. I'd rather not trust a program or utility to switch everything. I guess that being said since I'll have to go to the trouble of a fresh install is it even worth doing or are the benefits negligible?
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  4. #4



    Trying to Sith things out
    Bamberg Germany
    Posts : 2,288
    Windows 10 Pro 64 bit


    UEFI BIOS Advantages:


    1. When the option is available to choose between a Legacy BIOS boot mode or UEFI boot mode operating system installation, the advantages to choosing a UEFI boot mode installation include the following:
    2. Avoids Legacy Option ROM address constraints. For more information, see Legacy BIOS Option ROM Allocation Considerations.
    3. Supports operating system boot partitions greater than 2 terabytes (2 TB) in size.
    4. PCIe device configuration utilities are integrated with Setup Utility menus. For more information, see BIOS Setup Utility Screen Reference .
    5. Bootable operating system images will appear in the boot list as labeled entities, for example Windows boot manager label versus raw device labels.



    Benefits of UEFI boot mode over Legacy BIOS boot mode include:

    1. Support for hard drive partitions larger than 2 TB
    2. Support for more than four partitions on a drive
    3. Fast booting
    4. Efficient power and system management
    5. Robust reliability and fault management
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  5. #5


    Posts : 5,360
    7/8/ubuntu/Linux Deepin


    No benefits to mbr?

    No drawbacks to EFI?
      My System SpecsSystem Spec

  6. #6


    Having operated both on the same system, I would say that there isn't any advantage to MBR.

    I couldn't say for certain, but my system might be booting, and waking from sleep, just a little faster now that I am using UEFI / GPT.
      My System SpecsSystem Spec

  7. #7


    Posts : 4
    Windows 8.1


    I do appreciate the responses and helpful info. I think I understand (at least partially) the benefits. Anyone care to voice an opinion on if it's worth the pain in the neck of doing a fresh install, keeping in mind I'd have to install all my drivers and programs again.
      My System SpecsSystem Spec

  8. #8



    Trying to Sith things out
    Bamberg Germany
    Posts : 2,288
    Windows 10 Pro 64 bit


    Quote Originally Posted by SIW2 View Post
    No benefits to mbr?

    No drawbacks to EFI?
    I found this article at Windows Secrets.
      My System SpecsSystem Spec

  9. #9


    Quote Originally Posted by TheCatandThePat View Post
    I do appreciate the responses and helpful info. I think I understand (at least partially) the benefits. Anyone care to voice an opinion on if it's worth the pain in the neck of doing a fresh install, keeping in mind I'd have to install all my drivers and programs again.
    I was going to hold off on switching from MBR to GPT until I upgraded to either 8.1 pro (if I ever do that), or Win 10. However, my attempt to install the Win10 preview alongside 8.1, in dual boot fashion, messed everything up. I decided to backup my data and documents, and reinstall Windows and all my programs as well.

    I can't say the benefits of UEFI/GPT are really worth the effort, but if you are in need of a weekend project to keep you busy, then go ahead.
      My System SpecsSystem Spec

  10. #10


    Posts : 4
    Windows 8.1


    Quote Originally Posted by yu gnomi View Post
    Quote Originally Posted by TheCatandThePat View Post
    I do appreciate the responses and helpful info. I think I understand (at least partially) the benefits. Anyone care to voice an opinion on if it's worth the pain in the neck of doing a fresh install, keeping in mind I'd have to install all my drivers and programs again.
    I was going to hold off on switching from MBR to GPT until I upgraded to either 8.1 pro (if I ever do that), or Win 10. However, my attempt to install the Win10 preview alongside 8.1, in dual boot fashion, messed everything up. I decided to backup my data and documents, and reinstall Windows and all my programs as well.

    I can't say the benefits of UEFI/GPT are really worth the effort, but if you are in need of a weekend project to keep you busy, then go ahead.

    Ok well I guess I will hold off until 10 comes out or until like you say I feel like having a weekend project. Thanks again
      My System SpecsSystem Spec

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