Dedicating One GPU for Physics and One for Graphics

Discussion in 'Mac Pro' started by snuffleupagus1, Oct 2, 2011.

  1. snuffleupagus1 macrumors newbie

    Oct 2, 2011
    So I have a mid 09 MPB with a 9600m GT and 9400m. It is my understanding SLI would make no sense between these cards, since downgrading the 9600 to the 9400 would overall reduce the performance.

    However I'm wondering, would dedicating one card, say the 9600m GT to PysX and the 9400m to graphics (or vice-versa) allow the 9600m GT to remain at a higher performance. Or is this the same exact thing as SLI.

    I found this kind of weird and surprisingly easy guide
    I didn't try it since I first wanted to know if it was even worth it.

    PS. Is there a community for the 9600m GT dedicated to improving game performance in bootcamp.
  2. yousifabdullah macrumors regular

    Jul 19, 2011
    (You probably intended to post this in the MacBook Pro forum, not the Mac Pro forum.)

    Under Boot Camp, in MacBook Pro computers with selectable graphics cards, the system will only enable the higher performing graphics card, disabling the other. There's an Apple knowledge base article on this: No Mac computer has support for NVIDIA SLi or Hybrid SLi, which is what you're describing. You also can't dedicate one graphics card to function as a physics processing unit.

    Now, here's the interesting part. Ars Technica found out that, while having the discrete graphics card active in Mac OS X, the dormant graphics card remains active as well and is perfectly usable for OpenCL operations. This means that an OpenCL enabled application will effectively utilize three processing units to carry out calculations: the main CPU, the discrete graphics card and the lesser performing integrated graphics card. Ars Technica's article can be found here: This blog might be of interest as well, since it talks about OpenCL and the utilization of both graphics cards in a MacBook Pro computer in detail:

    Hope this helps.
  3. goMac macrumors 603

    Apr 15, 2004
    You can totally do this. You just need to use software that allows for this. Mac OS X and that model MBP allow for running both cards at once. I've done software development that took advantage of both cards at once.

    (This doesn't mean you get things like SLI, but what you're asking is still possible.)

    In Windows, I have software set up in this exact configuration on both my Mac Pro and my Macbook Pro. Physics offloaded to the secondary GPU. I don't know of any Mac OS X software that actually allows for this option though, even though it is technically possible.

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