iMac Mid-2011 (A1311) Model won't boot

Discussion in 'Mac Basics and Help' started by brianm109, Oct 26, 2015.

  1. brianm109 macrumors newbie

    Oct 26, 2015
    I replaced my stock Seagate HDD with another HDD. Now when I turn on my Mac, the computer does its regular startup chime, but there is no video. A few seconds later, the fan goes on full speed and it just does that forever. I have already tried resetting the PRAM and SMB. I can't locate the diagnostic lights though.

    iMac Mid-2011 (A1311)
    16GB RAM
    i7 (Don't remember exact model)
    Radeon HD (Don't remember exact model)
  2. chscag macrumors 68020


    Feb 17, 2008
    Fort Worth, Texas
    First, your Mid 2011 iMac used an Apple proprietary Seagate hard drive and cable (thermal sensor). Unless you replaced it with the same drive, the fans will go full blast. There are ways around that - you can Google for the cure(s). The no video is likely an assembly error or you broke a cable or connector when taking it apart. Go to and review the take apart instructions.

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