"256MB of DDR3 SDRAM shared with main memory"?

Discussion in 'MacBook Pro' started by antster94, Sep 21, 2010.

  1. antster94 macrumors 6502a

    antster94

    Joined:
    May 2, 2010
    Location:
    London, UK
    #1
    Hey guys,

    Just wondered as I'm thinking of ordering a 2.66 Refurb 13" MBP. Whats the difference between having 256MB of DDR3 SDRAM shared with main memory and 256MB memory? Does it mean that I'll just have less RAM available to use?

    Sorry if it's a dumb question, don't know a lot about hardware.

    Anthony
     
  2. Hellhammer Moderator

    Hellhammer

    Staff Member

    Joined:
    Dec 10, 2008
    Location:
    Finland
    #2
    Shared memory means that it uses your RAM. For example, if you have 4GB of RAM, 256MB of that will be dedicated to the GPU thus you have only 3.75GB for other stuff. Discrete GPUs that can be found from 15" and 17" have their own GDDR integrated into the graphics card
     
  3. antster94 thread starter macrumors 6502a

    antster94

    Joined:
    May 2, 2010
    Location:
    London, UK
  4. rockstarjoe macrumors 6502a

    rockstarjoe

    Joined:
    Jun 2, 2006
    Location:
    washington dc
    #4
    I was just wondering the other day where a quarter of a GB of my memory was going... thanks for the info!
     
  5. WardC macrumors 68030

    WardC

    Joined:
    Oct 17, 2007
    Location:
    Fort Worth, TX
    #5
    Hellhammer answered this very well. When you have shared memory for the graphics controller, like on my Mac Mini, instead of showing that the machine has 2GB of RAM in Activity Monitor, it shows that I have 1.75GB of RAM. 256MB is shared for the graphics controller. The 15" and 17" MacBook Pro have a dedicated discrete nVidia graphics card with its own memory on the graphics card, so the CPU can take full advantage of 100% of the installed RAM in the machine. No shared memory.
     

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