weird graphical glitch on Start up?

Discussion in 'OS X Mountain Lion (10.8)' started by Goobis, Aug 29, 2013.

  1. macrumors newbie

    Aug 29, 2013
    So I just upgraded my 27" iMac to Mountain Lion last week and now every time I boot up my mac there's this weird rectangle graphic distortion that pops up right as the apple sign appears. After it loads everything is fine and I can use my mac normally. Im just curious what it is. It never happened before Mountain Lion. Any ideas?

    Mac specs:

    27" iMac
    OSX: 10.8.4
    Processor: 3.4 GHz intel core i7
    memory: 12GB
    graphics card: AMD Radeon HD 6970M 2048mb


    Attached Files:

  2. macrumors 6502


    Jun 14, 2009
    San Francisco Area
    Strange indeed. Try a SMC reset and see if that fixes it.
  3. macrumors newbie

    Oct 27, 2013
    I am seeing a similar issue during boot on my MacBook Pro 2011. Faulty GPU?

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