GPT/EFI vs MBR/BIOS and Win8

Discussion in 'Memory and Storage' started by wpcoe, Sep 30, 2013.

  1. wpcoe

    wpcoe Senior member

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    I'm having a heck of a time installing Windows 8 Pro on a new SSD.

    My previous (until today) configuration was Win8, apps, and some data on a 120GB SSD and various data partitions on a 1TB HDD, both drives using MBR.

    I have a bootable Win8 installation USB thumb drive (which I used to install Win8 on my old SSD using MBR) and I can only get it to install on the fresh new drive as GPT. I don't mind that, but when I then plug in the MBR HDD and reboot, I either get an endless boot loop or a Windows Repair routine that fails. Ditto if I try to boot up with on the new GPT SSD and have the old MBR SSD connected.

    On my system I can NOT mix MBR drives with a boot Win8 GPT drive for some reason.

    If I set the "BIOS" back to "Legacy" -- i.e. not EFI, but old fashioned BIOS -- I cannot boot from the Win8 installation USB stick.

    The most irritating part of this is that I had this same problem before when I first installed Win8 on the old SSD a year ago, but found some workaround, and now I've forgotten what it was. Any ideas?

    I recall when I posted on some earlier thread people assured me that a Win8 GPT installation can coexist with and read MBR drives, but that is NOT my experience.

    So, how can I install Win8 fresh on my new SSD and still have my old HDD and SDD be usable and readable without converting them to GPT and losing over 1TB of files in the process?

    I want a fresh Win8 installation as some strangeness has crept into my setup, and I'm overdue for my annual computer housecleaning anyway. But, if need be, I'll clone the old SSD which is configured as MBR.

    PS: In case it's not clear, I'm installing Win8 from the USB stick with only the new SSD connected. The old SSD and the HDD are disconnected during the Win8 installation process. It's only after Win8 is completely installed and I've rebooted that I then try to boot with either, or both of, the old MBR drives connected.
     
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  3. razel

    razel Golden Member

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    Sounds like a boot order problem. You can try to change the boot order settings in your BIOS. Ensure your Win8 SSD is the 1st one. If that's the case, you'll need to re-create your Boot Configuration Data.

    Startup the Win8 DVD and get to a command-prompt. The quickest way is shift-F10 or shift-F11. Have fun with BCDEdit.
     
    #2 razel, Sep 30, 2013
    Last edited: Sep 30, 2013
  4. Insert_Nickname

    Insert_Nickname Platinum Member

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    You should remember that on windows MBR takes precedence over GPT when both are used. You may have inadvertently installed the bootloader to the MBR disk. Windows is slightly unpredictable where it place the bootfiles.

    The best course is to temporarily remove the MBR disk, then boot from DVD/USB and, like razel wrote, run BCDEdit to fix the bootfiles. When you're done reconnect the MBR drive and boot to windows.

    If you need to reinstall windows, make sure only the system drive is connected. That way the bootfiles can only end up in one place.
     
  5. wpcoe

    wpcoe Senior member

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    I am selecting the Win8 installation USB drive by accessing the boot device menu via <F12>. The only drives attached are the blank SSD and the USB thumb drive.

    You mean, like this?

     
  6. Insert_Nickname

    Insert_Nickname Platinum Member

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    Yep... :)

    The BIOS may be trying to boot from the wrong drive, when you plug the old drives in. Its a little difficult to say anything general about UEFI configuration. There should be a "boot" section or similar in your UEFI, where you can set boot priority for different drives. What brand is your mainboard?

    If you using F11/F12 for the boot menu, you're overriding your UEFIs boot config.