Triple Booting Windows 8 on Second Hard Disk

Discussion in 'Windows, Linux & Others on the Mac' started by iamcarl4ever, Sep 2, 2012.

  1. iamcarl4ever macrumors newbie

    Sep 2, 2012
    Hi all,

    I have an Early 2011, 15 inch MBP and want to dual boot Windows 8 and Mountain Lion. Currently I have a 750GB HDD installed and have just recently replaced my SuperDrive with a 256GB SSD.

    The 750GB HDD is partitioned so that Windows 7 takes up 512GB and Mountain Lion has the rest and I would like to install Windows 8 to the SSD so I can migrate files across from Windows 7 at my leisure.

    The problem is Windows 8 is giving me an error as follows:

    "Windows cannot be installed to this disk. The selected disk is of the GPT partition style"

    Is there a way I can triple boot? If not how can I set up my disks so that Windows 8 runs on the SSD and Mountain Lion on the HDD?


  2. murphychris macrumors 6502a

    Mar 19, 2012
    Apple hardware presents a CSM (legacy BIOS) to Windows. Windows booted in BIOS mode requires MBR. Your SSD is using GPT partitioning scheme. You need to use MBR. Then it might work.

    The problem is Apple's CSM allows for no user settings, so I don't think it's possible for two Windows installations to co-exist at the same time because there's no means to choose which one to boot. The CSM will only boot the first Windows it finds; and the option/alt menu on startup doesn't present multiple Windows disk icons (it will present a separate option for El Torito, i.e. DVD, if present, but not two HDD icons). This may also be firmware dependent as I've seen different behaviors on different models of Apple hardware.

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