renai42

Q: Mid-2015 iMac won't reboot into Windows 10 install

hi folks,

 

I have a brand new, mid-2015 Retina 27" iMac.

 

I'm trying to install Windows 10 (or, really, any version of Windows) on it via Bootcamp in a dual-boot scenario, so that I can do some gaming via Steam.

 

I have downloaded the latest Windows 10 iso from Microsoft.

 

Bootcamp Assistant partitions the drive, but when it reboots, it does not go into the Windows 10 installer. Instead, there is a delayed booting period, and then it dumps me back into Mac OS X. Holding down option does not show a Windows 10 bootable option. However, the drive has been partitioned -- the Windows partition shows up on the desktop in Mac OS X and in Disk Utility.

 

I know that Microsoft recently updated the Windows 10 isos, and I suspect what is happening here is that Bootcamp Assistant has not yet caught up.

 

I also suspect this problem is quite widespread.

 

Can anyone let me know what I should do? I also have a Windows 7 disk, but Bootcamp Assistant tells me I need Windows 8 minimum ... and Microsoft no longer sells copies of Windows 8.

 

Kind regards,

 

Renai

iMac, Windows 10

Posted on Dec 30, 2015 6:21 AM

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Q: Mid-2015 iMac won't reboot into Windows 10 install

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  • by Loner T,

    Loner T Loner T Dec 31, 2015 5:17 PM in response to renai42
    Level 7 (24,307 points)
    Safari
    Dec 31, 2015 5:17 PM in response to renai42

    Install the OS using EFI Boot from the W10 USB Installer. Create a partition using DU as Free Space and choose it when using the W10 installer. You will have the Apple Bootmanager booting two EFI OSes. You can also install Linux using EFI boot as well.

     

    Do not install any OSes with BIOS/MBR needs.

  • by renai42,

    renai42 renai42 Dec 31, 2015 5:41 PM in response to Loner T
    Level 1 (0 points)
    Dec 31, 2015 5:41 PM in response to Loner T

    "Install the OS using EFI Boot from the W10 USB Installer. Create a partition using DU as Free Space and choose it when using the W10 installer. You will have the Apple Bootmanager booting two EFI OSes. You can also install Linux using EFI boot as well."

     

    Wow -- that does sound easy, compared with using the buggy Boot Camp Assistant. Awesome.

     

    However, just to check -- what about drivers? Will Win10 handle the driver situation on a 2015 iMac at least to get to the point where I can install Apple's package in it later on?

  • by Loner T,

    Loner T Loner T Dec 31, 2015 5:44 PM in response to renai42
    Level 7 (24,307 points)
    Safari
    Dec 31, 2015 5:44 PM in response to renai42

    Once Windows is installed, download drivers using BCA and install them on the Windows side.

  • by dialabrain,

    dialabrain dialabrain Dec 31, 2015 6:09 PM in response to renai42
    Level 5 (6,386 points)
    Mac App Store
    Dec 31, 2015 6:09 PM in response to renai42

    FWIW, when BCA created the USB installer, it also added a Boot Camp folder on the USB drive containing the Apple drivers. Once Windows 10 was installed I just installed the drivers from there.

  • by renai42,

    renai42 renai42 Dec 31, 2015 8:59 PM in response to Loner T
    Level 1 (0 points)
    Dec 31, 2015 8:59 PM in response to Loner T

    One final question - how would you recommend creating a Win10 USB installer? Boot Camp Assistant doesn't give me the option. There are a few Windows-oriented guides to doing it online ... is there a recommended way in Mac OS X?

  • by dialabrain,

    dialabrain dialabrain Dec 31, 2015 9:12 PM in response to renai42
    Level 5 (6,386 points)
    Mac App Store
    Dec 31, 2015 9:12 PM in response to renai42

    Not sure what you mean by "Boot Camp Assistant doesn't give me the option". That's what I used to create one. You need at least an 8GB USB flash drive.

  • by Loner T,

    Loner T Loner T Dec 31, 2015 9:32 PM in response to renai42
    Level 7 (24,307 points)
    Safari
    Dec 31, 2015 9:32 PM in response to renai42

    From https://help.apple.com/bootcamp/assistant/6.0/#/bcmp173b3bf2

    Depending on the model of your Mac, you might not need an external USB drive to install Windows (you’re asked for one when you prepare your Mac for Windows if it’s required).

    For such models, go to https://www.microsoft.com/en-us/software-download/home from a Windows PC, and it will let you use Media Creation Tool and give a you a bootable USB. The other option is to use Diskpart (requires a Windows PC) and ISO or use a tool like Rufus.

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