Is there any low latency RAM available?

Discussion in 'MacBook Pro' started by Blu101, Oct 28, 2010.

  1. Blu101 macrumors 6502a

    Blu101

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    Sep 10, 2010
    #1
    Like the high performance one offered by OWC for the macbooks? Anything like that out there for the MBPs?
     
  2. jav6454 macrumors P6

    jav6454

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    #2
    RAM latency for laptops makes no difference. Only if you run synthetic benchmarks are you going to notice the difference. However, in real world, no difference. However, don't buy CL 10 RAM, that will be noticeable.
     
  3. Blu101 thread starter macrumors 6502a

    Blu101

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    Sep 10, 2010
    #3
    Oh, ok. I was reading some stuff online about how people overclock their RAMs to make things "snappier" and all, but I don't want to mess with that, so I was wondering how come the old DDR2 RAMs for Macbooks had a low latency option but none for DDR3 RAMs.

    On a RAM related topic, there was a thread I caught here in the forums a few days back about how MAC OS X starts with the 32 bit kernel and you have to hold down some buttons for it to start with the 64 bit kernel, and people were talking about RAM limitations between the kernels. Can the 32 bit kernel use the full 8GBs of RAM that we can upgrade to? That part was a bit confusing for me..
     
  4. jav6454 macrumors P6

    jav6454

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    #4
    The first has to do with the transfer speeds and inherent parallelism access time delays. Manufacturers try to release faster speeds, but the tradeoff is higher latency issues.

    The current kernel for OS X is 32-bit. Meaning the kernel will never access more than 3.25GB of RAM. That is no problem since the kernel barely goes over 20MB RAM footprint. However, the rest of the system, applications and processes do need space. Because of that OS X was (or rather is being) transitioned into 64-bit. Almost all (if not all) current Kernel extensions (kexts) are 64-bit. Furthermore, many native OS X applications are already 64-bit. That means they can use more than 3.25GB RAM without problems. Also, any application that needs 64-bit support will find it due to the revised kexts.
     
  5. Blu101 thread starter macrumors 6502a

    Blu101

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    Sep 10, 2010
    #5
    Ok, let's see if I get this right - the current 32 bit kernel with today's apps, many of whom are 64 bit, can in fact make use of the full 8GBs of RAM? Is that right?

    I think the lowest I've see on the iStat pro widget was ~1.7GB available (rest was used or tied up). It usually floats around 2GB-2.5GB free/available. Has anyone with the 8GB upgrade observed the extra RAM being used with the 32 bit kernel running the apps?
     
  6. terrymr macrumors member

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    Jul 11, 2006
    #6
    Correct.
     
  7. mulo macrumors 68020

    mulo

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    Aug 22, 2010
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    #7
    now I don't use the 32 bit kernel, but I have had a 24gb swap file :p
    aperture was leaking, badly.
    I still use all 8GB on a regular basis, although I do nothing really ram intensive, like photoshop or video editing.
     
  8. toxic macrumors 68000

    Joined:
    Nov 9, 2008
    #8
    the 32-bit kernel is not limited to 3GB. it uses PAE, so it can address up to something like 16GB.
     

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