6750M... has anyone confirmed memory sharing w/ system RAM?

Discussion in 'MacBook Pro' started by Ceebee1980, Mar 30, 2011.

  1. Ceebee1980 macrumors regular

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    Chatsworth, CA
    #1
    Hey, was just wondering if anyone had confirmed whether the video card will actually borrow system RAM? I'm considering going from 4 to 8 gigs, and have heard various things.

    Thanks!
     
  2. grahamnp macrumors 6502a

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    Jun 4, 2008
    #2
    Discrete GPUs don't use system RAM, so no, it would not.
     
  3. iLog.Genius macrumors 601

    iLog.Genius

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    #3
    From what I've read from numerous posts/users here, the discrete card, in this case the Radeon 6750M isn't and shouldn't be using any system RAM, it has it's own memory BUT because there is the Intel HD GPU which is integrated, that GPU uses system RAM and even though it's not in use, it will always occupy whatever memory it uses so if the Intel HD GPU uses 256 MB, that will always be used from RAM.

    That's what I've read and understood. I could be wrong though.
     
  4. Ceebee1980 thread starter macrumors regular

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    Mar 30, 2011
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    #4
    Wow.. interesting, I hadn't even considered that.
    So it's possible that increasing RAM could make the computer run cooler, by elevating the kick-in threshold of the discrete GPU?
    Meh, maybe I'm overthinking things. I bet the GPU algorithm is probably based on some set numbers of calculations or something :D
     
  5. iLog.Genius macrumors 601

    iLog.Genius

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    #5
    RAM doesn't control when the discrete kicks in and doesn't make your computer run any cooler. If you add more RAM, the main benefit is that you would be able to run more applications without having any slow downs but in terms of GPU utilization, it doesn't do anything for you.
     
  6. Mackilroy macrumors 68040

    Mackilroy

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    Jun 29, 2006
    #6
    The HD 3000 actually uses 384 MB of system memory. Otherwise you're right. :)
     
  7. grahamnp macrumors 6502a

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    #7
    No, the discrete GPU kicks in when OSX thinks a GPU intensive task is being performed, the amount of RAM available to the HD3000 has no bearing on this.
     
  8. mulo macrumors 68020

    mulo

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    #8
    nope, kicks in when OpenGL or OpenCL gets called.
     
  9. Derango macrumors regular

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    Feb 25, 2011
    #9
    Also, this isn't entirely true either. Discrete GPUs have the ability to use main system RAM if they need to (their own memory becomes full and they need more). They just don't unless it's absolutely necessary.
     
  10. c1phr macrumors 6502

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    Jan 8, 2011
    #10
    If you really want your computer to run cooler, download Gfxcardstatus and just force the Intel GPU when you aren't doing graphic intensive stuff.

    Otherwise, adding more ram will not change the activation time of the discreet GPU.
     
  11. superfula macrumors 6502

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    Mar 17, 2002
    #11
    It kicks in when ANY advanced graphics frameworks are called, which includes OpenGL, Core Graphics, Core Image, Quartz Composer, etc.
     
  12. c1phr macrumors 6502

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    Jan 8, 2011
    #12
    Yea, and it's not always necessary, which is extra annoying. Chrome and FF4 both call the discreet card since they initialize WebGL when they start. Then they can't make up their mind while you browse and toss back and forth depending on certain elements on a given page (flash is the main culprit).

    Because of this, I just got used to keeping mine on Intel unless I know I need my discreet gpu.
     
  13. lewdvig macrumors 65816

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    #13
    it's GDDR5 too. Run GPUz in windows and there is all the evidence that you need.

    The 6750M's VRAM bandwidth dwarfs what system RAM can offer.

    Also OT it is nice to see the ignorant trolls on this board who have claimed that VRAM capacity was not important have now all crawled back under their rocks.
     
  14. iMacDragon macrumors 65816

    iMacDragon

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    #14
    I for one was VERY glad to see apple finally ship a system with a proper amount of graphics ram, even if only on the higher end system.. I still consider the whole 256mb thing to be incredibly stingy considering the price of ram and virtually everyone else shipping at least 512mb+ on even lower end graphics chipsets nowadays.
     
  15. DustinT macrumors 68000

    DustinT

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    Feb 26, 2011
    #15
    While I do agree with you, I have been very pleasantly surprised with the performance of the 6490. I can easily play TF2 at 1080p with medium settings and have great performance. I didn't expect to be able to do that with 256m ram.
     
  16. grahamnp macrumors 6502a

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    Jun 4, 2008
    #16
    It's mostly a gimmick. You are really just disadvantaging yourself if you plan to run something that needs more than 256mb on a lower end GPU. Once you take the resolution of the computer in question into account, 256mb for a 6490 is fine. Yes it is stingy overall, but the 6490 is the bottleneck here, increasing the VRAM wouldn't yield as large an improvement as a marginally better GPU.
     
  17. iMacDragon macrumors 65816

    iMacDragon

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    #17
    I agree with this to a large extent, too, but realistically speaking even a 'lower' end gpu nowadays is perfectly capable of handling 512mb's worth of textures in a game, considering doom 3 could use this much 6 years ago.
     

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