Please help: iMac could not detect Windows 7 bootable USB on Startup manager

Discussion in 'macOS' started by Dataexar, Jan 7, 2012.

  1. Dataexar, Jan 7, 2012
    Last edited: Jan 7, 2012

    Dataexar macrumors newbie

    Jan 7, 2012
    Hi, recently I bought a 2011 Mid iMac 27" inch, running Mac OS 10.7.2

    I want Windows 7 on my iMac, install Windows via Bootcamp. I've done this on my 2011 11"inch Macbook Air (Running Mac OS 10.7.2) and my mid 2011 Mac Mini (also running Mac OS 10.7.2), the whole installation process was fine.

    After creating the USB, I chose "Install Windows 7". A blank white screen appears for a minute, then a message appears in black background "No bootable device -- Insert a bootable device then press any key". I tried all the USB port at the back of the iMac, the iMac could not detect it. :mad:

    The screen stuck, I cannot exit. I hold down the Power key for 5 seconds, turn on the Mac again. Hold down the option key, the startup manager appears, it only show two disk: Macintosh HD and the Recovery Disk. The USB should appear on the startup manager.

    I then plug in both the bootable USB into my Macbook Air, reboot, hold down option key, and the USB appears on the Startup Manager.

    What's wrong with the iMac? :confused:

    Please help!
  2. cstout macrumors newbie


    Sep 2, 2011
    Re: Please help: iMac could not detect Windows 7 bootable USB on Startup manager

    Nothing is wrong with your iMac. Your particular model was designed not to boot any external devices that are not GUID. Boot Camp is designed to only boot discs for computers that have an optical drive. The computers without optical drives (by design, not by modification) are meant to use Boot Camp via USB installation only.

    I tried all the wonderful tricks for the MacBook Pro's out there who wanted to modify the Info.plist for Boot to allow USB creation, but even though I successfully made that modification, my iMac still doesn't support booting that type of volume via USB. I even tried refit and it proceeded to the same error repeatedly, "No bootable device."

    All of my efforts were using known-good ISO's and known-good USB drives. Multiple ISO's and drives were tried. Fortunately, I took on the project to find a way to complete the installation without an optical drive (in the event of failure or modding). I ended up reverting everything to Apple-defaults, removed all modifications and refit, and completed the install with DVD only. I'm still looking for a work around for those who cannot use a DVD for installation in the iMac 21.5" or 27" Mid-2011.
  3. sorlaker macrumors newbie

    Mar 3, 2013
    Is it possible to set the Imac to boot from usb cd drive? Or it has to be Imac's superdrive? Help me cause mine is broken :(

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