9400M is not turned off in "Highe Performance" mode

Discussion in 'MacBook Pro' started by wbyung, Mar 1, 2009.

  1. wbyung macrumors member

    Jan 16, 2009
    I have found the following power usage stats from iStats menu bar in "Higher Performance" mode.

    GPU1 2.06W
    GPU2 2.97W

    The readings were taken while it is idling.

    I do suspect that switching from "Better Battery Life" would just "turn on the 9600M GPU and that there is no implementation in the ASIC to turn off the integrated graphics portion within the chipset.
  2. Quu macrumors 68030


    Apr 2, 2007
    Its impossible to turn the 9400M off as it is not only a GPU but also a system Chipset. If the 9400M turned off your laptop would also turn off as there would be nothing to link the CPU to the RAM the Hard Disks or any other component. ;)

    What is more likely is when you select the 9600GT the 9400M goes in to a low power mode or shuts off some of its Shader Cores that drive the GPU portion of the chipset.
  3. J the Ninja macrumors 68000

    Jul 14, 2008
    Also, read this:


    In the standard dual-GPU setup, the display is supposed to always remain attached to the IGP. I'm not sure Leopard actually does it this way though. (System Profiler seems to say the 9600 drives the display directly when it is enabled).

    In any case, what Quu said is the main reason.
  4. alphaod macrumors Core


    Feb 9, 2008
    Also if you turn off the IGP, then hybrid SLI wouldn't be possible.
  5. Abstract macrumors Penryn


    Dec 27, 2002
    Location Location Location

    This is the same old integrated graphics Apple (and other companies) have used in the past. The benefit of this new integrated graphics is that it has the power of a separate 9400 M video card from Nvidia.

    If it was a discrete graphics card, then I guess they'd be able to shut it off.

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