8GB RAM is not a hardware limit. It is software!

Discussion in 'MacBook' started by Jesseeee, Feb 9, 2011.

  1. Jesseeee, Feb 9, 2011
    Last edited: Feb 10, 2011

    macrumors newbie

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    #1
    Folks,

    Though this forum doesn't see as much technical stuff as the one for Mac Pros, I thought you might be interested in this.

    I bought 2x4GB Crucial RAM sticks so I could deal with the fact that SL 10.6.6 pages rather quickly with only 2GB of RAM.

    When I installed them and then fired up several VMs, I noticed that every time I used more than 4GB of RAM, it kernel panicked. Then, when I turned it off and then on again, it stayed with a blank screen and beeped once. I reseated the RAM and then tried again. Same result; kernel panic. I did learn that after a kernel panic, if you reseat the RAM, you can boot again.

    So right now you're thinking, "okay dummy, everyone knows you can't use more than 4GB in the Macbook 5,2." But hold the phone, because I booted up Windows 7, and it worked perfectly.

    I ran a bunch of VMs and opened all the programs I could think of, until I had less than 1GB free. So at least 7GB was in use, and it worked great. I tried the Windows Experience or whatever it's called that assigns number values to your hardware specs. The RAM passed the test fine. I also tried another program, Performance... something or other... The RAM was fine.

    [pics or it didn't happen, right?]

    Note that the Total ram is 8GB, and available is 1.2GB (free).

    So what this means is that any claims of "this is a hardware issue" are just not true. It could just be that the Macbook 5,2 Snow Leopard kernel is just hard-coded for 4GB, and crashes whenever trying to address RAM at any higher location.

    Tests with the 64-bit kernel of Snow Leopard are pending. Tests with 64-bit linux are pending.
     

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  2. macrumors 68030

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    #2
    That doesn't prove that the RAM limit is software based at all. Because, under SL, it sees all 8 GB, right? From what I understand, its actual limit is 6 GB, which is probably why you're having issues with 8 GB. I have 6 GB RAM in my MacBook 3,1 and never had a single problem, even though it's over the 4 GB Apple says is the limit.

    The reason you're having issues is because you've got too much RAM in your MacBook. It is definitely a hardware issue. Not sure why Windows isn't freaking out too, though.

    If it were truly a software issue, it would just not function, or prevent you from seeing the extra RAM, or something like that. It's kernel panicking because of a hardware issue. This is certainly an interesting situation, though, so I'm interested to see what your OS X and Linux tests return.
     
  3. thread starter macrumors newbie

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    #3
    Did you read the post? Windows isn't freaking out at all. It's working great. I am proving that I can use all the RAM without a kernel panic.
     
  4. macrumors 6502a

    blackburn

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    #4
    It might be a drivers issue. Maybe the windows driver has somekind of fix for an chipset bug that may exist.

    Anyway nice find:cool:
     
  5. macrumors 65816

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    #5
    I thought this was common knowledge now.

    THe ONLY way it would be a Hardware issue is if Apple itself crippled the hardware. the same hardware is used in MANY laptops and easily supports 8GB. Apple is the ONLY maker with 4GB and 6GB limits any more.

    They falsely limit your RAM and they falsely limit you to 32-bit on a system that supports 64-bit. All just to get you to pay more for the Pro line.
     
  6. macrumors 6502a

    blackburn

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    #6
    He could try and use an hacked boot.efi, and try to run it in 64bits mode. Maybe with some more hackery try to change the model id to an macbook pro.
     
  7. thread starter macrumors newbie

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    #7
    Leopard works

    So I just tried doing a memory test with 8GB with Leopard, and it worked well. It appears that it is most certainly a memory management error in Snow Leopard. Maybe the way they did PAE on SL is flawed. So until I can get a working 64-bit Snow Leopard kernel to work, I'll just use Leopard and Windows7.

    Summary: as of February 2011, for the Macbook 5,2 White Early 2009, 8GB RAM works on:
    10.5.8 Leopard
    Windows 7 x64


    Does not work on:
    10.6.6 Snow Leopard 32-bit
    Ubuntu Lynx 32-bit (need further verification; didn't try very hard to get it to boot)
     

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  8. macrumors 6502a

    blackburn

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    #8
    In ubuntu you need to install an special kernel to use the full 8gb. I've posted the hacked boot.efi in another thread if you need.
     
  9. macrumors 68030

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    #9
    Did you read mine? ;)

     
  10. macrumors 65816

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    #10
    Yours is a crock. If it was the hardware then where are the Core2Duo based WIndows laptops with the same chipsets that freak out with 8GB of RAM?

    Oh wait ONLY Apples do that.

    If there is ANY fault in the hardware it's in Apple motherboard design. How ever remember that the unibody MacBook used to have the same problem until 10.6.6 came out. Then it suddenly worked. Heck the 13in Alu MacBook and 1st gen 13in pro were identical laptops, but the Alu MacBook ccouldn't do 8GB the Pro could.

    Apple plays these games all the time.
     
  11. macrumors 603

    chrmjenkins

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    #11
    8GB is the limit because 8GB sticks doesn't exist yet ;)
     
  12. macrumors 68030

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    #12
    If I'm wrong, I'll admit it. My understanding is that it's a hardware issue (even if artificially imposed), not software. Calling it a crock, however, does nothing to prove that point. I know of no Windows laptops with the same exact chipset as a MacBook. Because none of them are a MacBook.

    I'm perfectly willing to admit that Apple may have arbitrarily imposed a RAM limit, but I'm pretty sure it's on a hardware level, not a software level. If I'm wrong, then I'm wrong. We learn best when we're wrong. The question here is not the morality of such a limit, but simply whether or not it exists.
     
  13. macrumors 65816

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    #13
    Exact chipset? The 9400m chipset was in quite a few PC laptops. The only change in the new macbook is the GPU in the chipset was changed to the 320m instead of the typical 310M everyone else uses. The more I look at the 320M the more it looks like a GeForce GT 325M with integrated memory instead of dedicated.

    9400m = supports 8GB in every non-Apple laptop, Apple only allows 8GB to work in the Pro 13in. Limited the white/Alu Macbook to 6GB, until 10.6.6 came out.

    Apple doesn't use any special chipsets that no one else does. The ONLY chance this would have been a hardware issue is if Apple altered the hardware. Which they can't do legally so they limit it in software. The only control that Apple has over the physical chipset is the placement the want it on the Logic board. The fact that an OS X update can allow 8GB to suddenly work further proves its a software error.

    As for why OS X will boot and show 8GB and fail when trying to access over 6GB while Windows does not is most likely due to the way OS X and Windows talk differently to the systems EFI. I believe that OS X and the EFI(both written/heavily modified by Apple) argue when laptops Apple says dont support over 4GB when it gets to the 6GB point as they must have put a limiter in it some place. Windows probably doesn't get this error as the EFI isn't as integrated to Windows as it is to OS X.

    It's similar to a car's MPH limiting. My Ford Escort can physically do over 106MPH but when it gets that fast is bucks and shudders because the computers software see's 106MPH and then starts to limit the engine by cutting fuel, and such to prevent acceleration. Without the software limit it can go to 120+MPH. Only on OS X since it can't "buck and shudder" it just locks up or crashes.
     
  14. thread starter macrumors newbie

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    #14
    Oh haha, I suppose I didn't! :p
     
  15. macrumors 68030

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    #15
    Point taken, altecXP. Looks like it may be a software issue, and I was mistaken. By "exact chipset" I was referring to the whole board, really, but I guess that's probably not accurate to the phrase.

    FWIW, people have been successfully getting 8 GB RAM to work in the white unibody MacBooks (Late 2009 and later) well before 10.6.6 came out.
     
  16. macrumors member

    aniketroxx

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    #16
  17. macrumors 603

    chrmjenkins

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    #17
  18. thread starter macrumors newbie

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    #18
    Forget this entire thread!

    While gathering data to submit a bug report to Apple, I attempted to recreate the kernel panic that I got under Snow Leopard... but couldn't. Maybe the RAM needed to be broken in, or the 2nd DIMM wasn't cooperating. I don't know. But it works now.

    So, if you're a Macbook 5,2 owner, feel free to buy 2x4GB RAM sticks. It should work, after you've messed with it a whole lot.


    Or maybe I'll get a kernel panic tomorrow. If that happens, I'll post on this thread.
     

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  19. macrumors member

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    #19
    Sorry for bringing up an old thread. Will it work stable on e.g. Mavericks instead of SL?
     
  20. macrumors 6502a

    BrettApple

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    #20
    From what I can tell, it works fine now. I'm thinking it started working properly with updated firmware and the later releases of Snow Leopard. Mavericks should be fine. I had Yosemite on mine with 8GB for a test run and it was alright.

    On my Late 2008 it started with a firmware update and 10.6.6 and later. I'm thinking it's similar in these 2009 models as well, since they share the same chipset for the most part.
     
  21. macrumors member

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    #21
    But isn't it a major difference that the late 2008 uses DDR3 and mid 2009 uses DDR2?
     
  22. macrumors 6502a

    BrettApple

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    #22
    It's a major difference in performance and cost yes.

    But I believe they use the same chipset. The MCP79 to be more specific. It supports both DDR2 and DDR3. Obviously there is a physical difference with DDR2/DDR3 in the Late 2008 vs Early 2009 model, but it's the same controller and it should be able to address 8GB of RAM on both models.

    You can always try it and if it doesn't work return it. Assuming you get it from a seller that has a good return policy, and most do. Otherwise, depending on what you're using this for, 4GB may still suffice. Biggest boost is with lots of multitasking, Virtual Machines, big files in apps like the Adobe CS suite, and the like. The bottleneck in the 2009 models is going to be the 9400m GPU and then the aging Core 2 Duo. Though it's still very capable.
     
  23. macrumors member

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    #23
    ok thanks for the help. I will check it out and see what happens. :)
     

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