Does External display or Bootcamp always trigger dGPU?

Discussion in 'MacBook Pro' started by johngwheeler, Nov 14, 2014.

  1. johngwheeler macrumors 6502

    Joined:
    Dec 30, 2010
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    I come from a land down-under...
    #1
    Sorry, yet another dGPU question!

    Can anyone confirm that either running Windows via Bootcamp, or connecting an external display will force use of the dGPU in the mid/high-level rMBP 15?

    I nearly always use an external monitor, except when travelling, so I don't want to find myself generating unnecessary heat when I don't actually need the dGPU (such as writing documents).

    I'm also concerned about running Bootcamp on battery power. If Windows always uses the dGPU (which I understand it does), then I would expect battery life to be much worse in Bootcamp than in Mac OS X. Is this true?

    Thanks,

    John.
     
  2. leman macrumors 604

    Joined:
    Oct 14, 2008
    #2
    AFAIK, the external display output is wired via the dGPU, so there is no way around it. And Windows does not have the drivers for Apple's video signal switcher. Someone did report successful recognition of both iGPU and dGPU using an EFI-enabled Windows 8.1 installation, but I can't give you any details on that.
     
  3. johngwheeler thread starter macrumors 6502

    Joined:
    Dec 30, 2010
    Location:
    I come from a land down-under...
    #3
    Hmmm, those are both negatives for me! I don't think I have a need for the dGPU for the apps I use, and I certainly don't want it activated permanently when I connect to an external monitor, unless it's giving me some significant advantage (I understand the Iris Pro is perfectly capable of running two monitors at 1920x1200).

    I've heard worrying things about excess heat, shorted battery life and potential unreliability, so I don't want to have all of that in exchange for some some capability that I will never use.
     
  4. snaky69 macrumors 603

    Joined:
    Mar 14, 2008
    #4
    Yes and yes.
     

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