I have the reason as to why the late 08 books only support 6GB

Discussion in 'MacBook Pro' started by Battlefield Fan, Nov 1, 2008.

  1. Battlefield Fan macrumors 65816

    Battlefield Fan

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    Mar 9, 2008
    #1
    Ok so as the title suggest I believe I found the answer.

    I think its pretty obvious that the limit set it because of hardware not software. mp's and xserves can run up to 32GBs of RAM.

    The new core i7 architecture is coming out within less than 6 months. This processor runs triple channel memory. This is achieved by installing 3 matching pairs of DIMS. This would make it affordable by installing three 2GB sticks.

    YES i realize that that the new notebooks arent the core i7 branding but maybe doesnt plan on upgrading the mainboard and they purposely set the hardware limit because of i7.
     
  2. J the Ninja macrumors 68000

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    #2
    Wut?


    The MCP79FX chipset has NOTHING to do with i7. It doesn't support it. No NVidia chipset does. End of story.

    The MBP does not support triple channel, it has only 2 RAM banks. Why? Because that's all the chipset supports. In fact, i7 supports triple channel because it uses an onboard memory controller (nothing to do with x58 directly), which makes it incompatible with any Core 2 board by default (Core 2 has no IMC, thus needing a Northbridge based one. If you had both, they'd conflict.)

    And with triple channel, you'd STILL have the 4GB DIMMs that caused this mystery in the first place, thus needing expandability to 12GB.


    In short, massive hardware-knowledge fail.
     
  3. raymondu999 macrumors 65816

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    #3
    Actually, Apple's been known to limit their RAM limits software-wise differently for different models. Hence the Mac pros can take 32GB while the MacBook Pros only 4
     
  4. Battlefield Fan thread starter macrumors 65816

    Battlefield Fan

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    #4
    i completely understand that the new mb's only have two sockets for memory but what im saying is it seems like they set up the limit for when THEY DO switch over to core i7.

    And your wrong with having to use 4GB DIMMS. First off no laptops could even take advange of triple channel because for 3 4gb dimms it would cost $1500.

    Also Im currently studying as a computer hardware engineer so its not a massive hardware knowledge fail.
     
  5. Eidorian macrumors Penryn

    Eidorian

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    #5
    What's the relation between the MCP79A and Core i7 again?

    You're not going to see triple channel memory on mobile or desktop Nehalem variants either. Yes, really.
     
  6. Battlefield Fan thread starter macrumors 65816

    Battlefield Fan

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    #6
    yes but they tend to only do that because of cost and reality. I honestly don't imagine anyone putting in more than 32gb's of ram into a mac pro and even at 32 GBs it will cost you $2400.

    You should look into things.

    Here is the triple channel memory: http://xbitlabs.com/news/memory/dis...mory_Modules_for_Intel_Core_i7_Platforms.html

    and here are th desktop mobos: http://www.theinquirer.net/gb/inquirer/news/2008/10/31/initial-nehalem-mainboards-asus

    notice the motherboards have 6 sockets for ram. Thus showing they will support triple channel memory
     
  7. Eidorian macrumors Penryn

    Eidorian

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    #7
    X58 and the LGA1366 processors will have triple channel memory.

    P55 and LGA1160 are dual channel.

    Calpella and with whatever socket it ends up with is going to be dual channel as well.

    Notice how there are different sockets as well as memory channels? Research more please...
     
  8. Battlefield Fan thread starter macrumors 65816

    Battlefield Fan

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    #8
    well you just said that you would never see triple channel memory and i just showed you that its already out. Ok so it might not make it into notebooks but IT IS CERTAINLY happening with desktops.
     
  9. Eidorian macrumors Penryn

    Eidorian

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    #9

    Did I need to spell out that X58 is Intel's enthusiast platform and not a consumer desktop one?
     
  10. Battlefield Fan thread starter macrumors 65816

    Battlefield Fan

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    #10
    who ever said we were talking about desktops? I mean I originally was talking about latops and then you said that your would never see it in desktops or laptops. And last i checked an enthusiast computer it a desktop SO NOW WHAT?
     
  11. Eidorian macrumors Penryn

    Eidorian

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    #11
    How does that relate to the 6 GB memory limit in laptops then?
     
  12. Eidorian macrumors Penryn

    Eidorian

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    #12
    My point is, if it didn't come across earlier, that there are many versions of Core i7. Some are going to have triple channel (Bloomfield/Gainestown) while others are going to have only dual channel memory (Lynnfield/Clarksfield).

    There are different IMCs in the mix and not to mention sockets. There's no relationship between the 6 GB limit in the current laptops and triple channel memory.

    If you're going to try to argue triple channel memory in a laptop, it isn't happening. Not to mention why would Intel add another memory slot if they're trying to make laptop motherboards smaller?
     
  13. cmatt macrumors member

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    #13
    not aimed at you mate ;) and i agree... ;) there is no need in the current climate to have the ability to spec out that much memory - no one would buy it.
     
  14. mknawabi macrumors 6502

    mknawabi

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    #14
    Eidorian is completely correct. Why would Apple create a motherboard that uses a nVidia northbridge chipset with integrated graphics and an integrated memory controller when Core i7 processors have those built into the processor? And to say that it provides Apple with a 'transition' is a crass statement, it does no such thing.

    Your logic makes no sense, Battlefield Fan. When Nehalem is introduced onto laptops, Apple will have to make a completely new motherboard revision.
     
  15. ayeying macrumors 601

    ayeying

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    #15
    So since theres a triple channel, that means I can install 3x4GB to make it 12GB total right?

    Look, its proven that 8GB works but the software has trouble understanding all 8GB without getting confused. Last time I checked (I could be wrong here), I haven't seen anyone complain about 8GB failing in Windows or any other OS other then OSX on a MacBook Pro.

    6GB works because the system doesn't seem to get confused which obviously means that there is some software or kernel issue.

    Now, this example might be completely different and way off but, on my MacBook Pro (and many other users have this also), a 32-bit Windows only sees 2.98GB-3.25GB. However, if you were to run a same 32-bit Windows Server 2003 Enterprise, you can read and use 3.98GB (Tested already) on a same 32-bit. It means that software issues for memory limit CAN happen, and it DOES happen regularly on many systems, not just the Mac lines. My Dell Vostro 200 desktop had a memory controller capable of 8GB but anything above 3.25GB is unusable. Why? I don't entirely know. It could be possible its a limit of software at the BIOS. Not even 64-bit unlocked the 3.25GB.
     
  16. Eidorian macrumors Penryn

    Eidorian

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    #16
    I've only seen 3 GB and 6 GB kits out right now for X58 based Nehalem systems. A 12 GB kit is logical but I don't have that kind of money. ;)


    That's strange since the G45 chipset should support 8 GB of RAM just fine.
     
  17. mknawabi macrumors 6502

    mknawabi

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    #17
    So why hasn't anyone tried Vista x64 or XP x64 with 8GB of RAM yet?
     
  18. Eidorian macrumors Penryn

    Eidorian

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    #18
    Cave Man tried Debian 64-bit but I forget where their results ended up.

    I'm still wondering where the Vista 64 tests are as well.
     
  19. ayeying macrumors 601

    ayeying

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    #19
    It should support 8GB, but I tried putting in 4/5/6/7/8GB total ram and it all reads 3.25GB in Vista x64. I got rid of that system because of that.
     
  20. Eidorian macrumors Penryn

    Eidorian

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    #20
    I've been looking at a few X58 single processor motherboard reviews and some of them do support 12 GB of RAM.

    Intel's DX58SO board supports 8 GB of RAM with 4 slots. Yes, really.
     

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