Windows 8 and 8.1 Forums

Convert MBR To GPT To Install Win 8.1

  1. #1

    Posts : 11
    Windows 8.1 Pro

    Convert MBR To GPT To Install Win 8.1

    Ok my daughters Acer laptop already has Windows 8.1 installed. It has a MBR disk. My USB Flash Drive won't boot from it but it does my my desktop so not the USB flash drive.The flash drive was created for UEFI or MBR boot using Rufus. I tried the tutorial in sevenforums to convert the Acer to GPT but it says the boot drive is in use and can't. I tried to boot to a Command Prompt but that gives me an X: drive and I can't change it to C prompt. I have done this before from a boot drive and it worked but won't on this machine. How can I get this converted from MBR to GPT??? How can they make that tutorial work for them? They are doing it from within windows there??? This machine BIOS has nothing for legacy or UEFI or secure boot for sure. Is my only option MBR then? If it is what do I make the flash drive with as Rufus option says for UEFI or MBR but won't boot this machine. Yes I have it to boot first but it lights up but goes straight to windows. Thanks for any insight here.

      My System SpecsSystem Spec

  2. #2

    San Jose - California
    Posts : 2,846
    8.1x64PWMC Ubuntu14.04x64 MintMate17x64

    The flash drive was created for UEFI or MBR boot using Rufus
    It will work for both but you have to change the BIOS to appropriate settings ie. MBR to use MBR type or UEFI for UFEI type.
    I tried the tutorial in sevenforums to convert the Acer to GPT but it says the boot drive is in use and can't
    You cannot convert from MBR to GPT while Windows is running. You can only convert when it is offline and in addition you will wipe out the data on the disk.

    I tried to boot to a Command Prompt but that gives me an X: drive and I can't change it to C prompt
    When you boot to a command prompt, you are booting to the Windows Recovery Environment (WinPE), the Drive letter is X: and it is in Ramdisk, it is different from your real drive C:

    FYI, As far as speed goes, it does not make any difference whether you use MBR or GPT. GPT supports large disk capacity > 2TB and more than 4 primary partitions can be created. For Laptop, MBR is fine.

    If you really insist to re-install using GPT, then just change the BIOS to UEFI then boot the Installation USB with UEFI mode. When you get to the screen to install Windows, select Custom Install, on next screen, select each partition an click delete untill you have 1 single unallocated partition then click New, Windows will initialize the disk as GPT & create 4 new partitions, just click next and continue windows installation.

    CAUTION: By doing this, you will wipe out everything on that disk including the Windows 8 OEM Recovery partition, so save anything that you need to save first.
    Last edited by topgundcp; 22 Jul 2014 at 00:25.
      My System SpecsSystem Spec

  3. #3

    Posts : 879
    Windows 10

    Quote Originally Posted by uffbros View Post
    The flash drive was created for UEFI or MBR boot using Rufus.

    Why doesn't Rufus create an USB that can be booted in both BIOS and EFI mode?

    If you are using an ISO that can be dual booted in EFI or BIOS mode, you may find that the USB created by Rufus will not preserve the dual EFI+BIOS boot feature.

    Especially, the Windows 8 installation ISOs, that support both EFI and BIOS boot, will be converted to either one or the other mode, depending on the option you selected under Partition scheme and target type: If you select the first option (MBR partition scheme for BIOS or UEFI computer), the USB will be bootable in BIOS-mode only (even on UEFI systems), and if you select any of the other options, the USB will be bootable in EFI mode only (and not bootable on a BIOS system at all).
    Here is more info:
    Windows 7/8 setup: Installing using the MBR or GPT partition style.
      My System SpecsSystem Spec

  4. #4

    Posts : 11
    Windows 8.1 Pro

    As stated in my original post.....This laptop BIOS has no UEFI setting. It doesn't have anything about Legacy either. I looked at every window in BIOS. I'll just make a MBR Flash Drive and be done with it. Just wanted to know if it could be done GPT. Thanks.
      My System SpecsSystem Spec

  5. #5

    Posts : 879
    Windows 10

    Windows 8 64-bit only support booting from GPT partitions on systems with UEFI firmware.

    Windows and GPT FAQ (Windows Drivers)

    Is UEFI required for a GPT disk?
    No. GPT disks are self-identifying. All the information needed to interpret the partitioning scheme of a GPT disk is completely contained in structures in specified locations on the physical media.

    Can Windows 7, Windows Vista, and Windows Server 2008 read, write, and boot from GPT disks?
    Yes, all versions can use GPT partitioned disks for data. Booting is only supported for 64-bit editions on UEFI-based systems.
      My System SpecsSystem Spec

Convert MBR To GPT To Install Win 8.1

Similar Threads
Thread Forum
Can I Convert My SSD (OS) Drive From MBR to GPT?
Hello All, I was playing around with this new program I bought called Paragon HD Manager. I ran it on my laptop which is only about one month old and has two hard drives: a Samsung 830 SSD (for the OS) and an HGST Travelstar HDD (for data). I then ran the program on my desktop PC which also...
Installation & Setup
Convert disk From MBR to GPT to install windows
I attempted to install windows from a USB, but it gave an error saying "Error: Windows Cannot Be Installed to This Disk. The Selected Disk Has an MBR Partition Table. On EFI Systems, Windows Can Only Be Installed to GPT." I disabled all EFI boot sources and safe boot, but the error is still...
Installation & Setup
music convert
Hi Hope im in the right place . i want to put some mp4 music on to a cd from my music files, do i need to convert it first please ,
Sound & Audio
How to convert cpt to mbr?
Ok I have my prompt saying DISKPART> so how do I get it to run on my f: drive. convert f: to mbr. Where do I tell or input that it is the f: drive..what would be the correct syntax?
Installation & Setup
convert x to dvd 4
just wonding if anyone can put me in the right direction on another softwear were i can convert any film file that i have downloaded from torrent and convert and then burn onto disc. it has to be for 32 bit thank u
General Support
Rip and Convert
I have an extensive video library which I am trying to put onto my computer. I am running windows 8. I have tried lots of programs and nearly all of them fail to produce good quality on the computer. All of them seem to break up and pixelate. I can remove some of the "VOB" files to the computer...
Software and Apps

Eight Forums Android App Eight Forums IOS App Follow us on Facebook