Iris Pro memory usage from base model iMac

Discussion in 'iMac' started by Ice Dragon, Sep 25, 2013.

  1. Ice Dragon macrumors 6502a

    Ice Dragon

    Joined:
    Jun 16, 2009
    #1
    I know it is probably too early to ask though perhaps not. How much memory does the Iris Pro graphics take from the main memory for 8 GB and 16 GB?

    Thanks in advance.
     
  2. iStiggy macrumors member

    Joined:
    Mar 24, 2013
    #2
    1024MB on the in store base model. It has 8GB of RAM.
     
  3. Ice Dragon thread starter macrumors 6502a

    Ice Dragon

    Joined:
    Jun 16, 2009
    #3
    Oh awesome. It actually gives the reading as 1024 MB or does it give it as 1 GB? Not that it matters since it's the same thing.
     
  4. iStiggy macrumors member

    Joined:
    Mar 24, 2013
    #4
    1024mb.
     
  5. jabalczar macrumors member

    Joined:
    Jul 22, 2011
    #5
    Excuse my ignorance, but does this mean there is not as much RAM (of the 8 GB) available to OS X because Iris Pro is using 1 GB of it?

    Whereas, on the 2012 model there was a dedicated graphics card and so the full 8 GB RAM was available to the system.

    For example, on my 2012 iMac OS X 10.8 used around 1.4 GB of wired RAM for the OS. Will this now jump to 2.4 GB because 1 GB is reserved for Iris Pro?

    Do this also mean potentially that if one uses programs that are uses a lot of RAM it might push the machine more to the limit as you near say 7 GB RAM usage?

    Thanks
     
  6. The-Pro macrumors 65816

    Joined:
    Dec 2, 2010
    Location:
    Germany
    #6
    you are more or less correct. When the gpu needs to use 1GB of vram then there will only be 7GB available for the system.

    have a read here: http://forums.cnet.com/7723-10149_1...ry-confusion-dedicated-shared-discrete-oh-my/
     
  7. jabalczar macrumors member

    Joined:
    Jul 22, 2011
    #7
    Thank you for the reply. In the link you provide it states:

    "Sharing main memory with the display function reduces the amount of memory available to applications, and main memory is not as fast as the specialized video memory on stand-alone cards."

    I'm assuming, however, that Iris Pro even though it's using shared memory will not be slower than the base dedicated NVIDIA card in the 2012 iMac?
     
  8. Ice Dragon thread starter macrumors 6502a

    Ice Dragon

    Joined:
    Jun 16, 2009
    #8
    No, the Iris Pro is faster. I think someone told me by at least 10-15%. Also thinking with the old Steve Jobs idea of "performance per watt", there was not enough to consider having 1 GB of the 740M in the base model or worse 512 MB of the 750M.
     
  9. iStiggy macrumors member

    Joined:
    Mar 24, 2013
    #9
    Iris Pro 5200 also has a 128MB cache for graphics only. It is located on the CPU die.
     
  10. wmy5 macrumors regular

    Joined:
    Oct 27, 2012
    Location:
    upstate NY
    #10
    Not exactly. Iris Pro has a eDRAM that can be accessed by both GPU and CPU. It's literally a L4 cache.
     

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