3GB or 2GB dual-channel?

Discussion in 'Buying Tips and Advice' started by Demon Hunter, Oct 24, 2006.

  1. Demon Hunter macrumors 68020

    Joined:
    Mar 30, 2004
    #1
    The new MBP and iMac support up to 3GB of RAM, but this disables the dual-channel capability (2GB, 2x1 GB). Does anyone know which is better? I'm thinking about performance in games, video editing, Photoshop rendering, etc.

    Also, why isn't 4GB supported? Is that a limitation of the Napa chipset?
     
  2. Umbongo macrumors 601

    Umbongo

    Joined:
    Sep 14, 2006
    Location:
    England
    #2
    There was supposed to be Napa 2 that enables core 2 duo to be used as a 64-bit chip, I saw dell touting their laptops as 64-bit and that you can use 4GB with a 64-bit operating system and lenovo and HP have 4gb options also. Now whether Napa 2 is a firmware upgrade or new boards I don't know and couldn't seem to find out just searching the web. Hopefully someone else can shed some more light on the technicalities of it.
     
  3. JAT macrumors 603

    Joined:
    Dec 31, 2001
    Location:
    Mpls, MN
    #3
    Dual channel isn't necessary on these computers. It is moderately useful on the Mini/MB with integrated graphics, but barely.
     
  4. Demon Hunter thread starter macrumors 68020

    Joined:
    Mar 30, 2004
    #4
    From what I've read, the increase in bandwith is quite dramatic, but apparently this doesn't affect system performance much? :confused:
     
  5. daneoni macrumors G4

    daneoni

    Joined:
    Mar 24, 2006
    #5
    I heard it was the other way round.
     
  6. xfiftyfour macrumors 68030

    xfiftyfour

    Joined:
    Apr 14, 2006
    Location:
    Clemson, SC
    #6
    ya heard wrong.
     
  7. Eidorian macrumors Penryn

    Eidorian

    Joined:
    Mar 23, 2005
    Location:
    Indianapolis
    #7
    Napa 2 or even 64 is still out there somewhere. Did we EVER confirm it's existence?
     
  8. JAT macrumors 603

    Joined:
    Dec 31, 2001
    Location:
    Mpls, MN
    #8
    The increase in bandwidth at a specific point in the RAM system is double if RAM chips are matched. But the way the overall system uses the RAM makes the real-world benefit tiny. You can search for the Intel white paper on the memory system if you want. It barely even mentions dual-channel issues.

    I have zero complaints about the speed of my wife's 1GB + 256MB RAM Macbook. WAY better than the stock 256MB + 256MB since Tiger really needs more than 512 to run much.

    Now, the Mac Pro is a different story.
     
  9. Clydefrog macrumors 6502a

    Clydefrog

    Joined:
    Feb 24, 2006
    Location:
    Pittsburgh,PA
    #9
    i doubt you will even notice anything if you lost dual channel
     
  10. Scarlet Fever macrumors 68040

    Scarlet Fever

    Joined:
    Jul 22, 2005
    Location:
    Bookshop!
    #10
    the extra gig of RAM will give you more of a performace boost than the fabled dual-channel RAM.
     
  11. Carguy172 macrumors member

    Joined:
    Oct 8, 2006
    #11
    It still is dual channel you have two dimms of ram it doesn't matter what size as long as you have two dual channel ram sticks.
     
  12. levitynyc macrumors 65816

    Joined:
    Aug 19, 2006
    #12
    I can't seem to find the thread, but someone posted a link with benchmark testing on a dual channel vs non dual channel RAM and they tested EXACTLY the same when not used with Integrated Graphics Cards.
     
  13. Eidorian macrumors Penryn

    Eidorian

    Joined:
    Mar 23, 2005
    Location:
    Indianapolis
    #13
    It's called http://barefeats.com/.
     
  14. Demon Hunter thread starter macrumors 68020

    Joined:
    Mar 30, 2004
    #14
    This says otherwise:

     
  15. levitynyc macrumors 65816

    Joined:
    Aug 19, 2006
    #15
    This entire discussion is faulty.

    In just about all Benchmark Testing, Dual Channel Ram shows no advantage over mispaired Ram in computers with non-integrating graphics cards.
     
  16. tarjan macrumors regular

    Joined:
    Aug 11, 2006
    #16
    break out a soldering iron and put those 1gb sims on the video ram. That'll show apple!
     
  17. TBi macrumors 68030

    TBi

    Joined:
    Jul 26, 2005
    Location:
    Ireland
    #17
    Dual channel will be enabled with memory sticks of different sizes. So as long as you have two sticks then you'll have dual channel.

    EDIT: Straight from the horses mouth! Dual channel is enabled with intels flex memory technology!

     
  18. Demon Hunter thread starter macrumors 68020

    Joined:
    Mar 30, 2004
    #18
    See post #14...
     
  19. JAT macrumors 603

    Joined:
    Dec 31, 2001
    Location:
    Mpls, MN
    #19
    What did you look up on Wiki? Just because some RAM buses are dual channel doesn't mean all of them are. And Wiki is not infallible.

    If memory serves:
    The mobile setup on most Intel Macs is not full dual channel like the Mac Pros, which won't even function without paired memory. It can make some use of memory interleaving, I believe. In which case speed is a bit higher with matching RAM. But it is only actually used with the models with integrated graphics cards. And it doesn't make that much difference in the first place. Maybe if you are a hard-core gamer with high video demands, but what are you doing with a MB in that case, anyway? Anyway, the thread asked about iMac and MBP with dedicated cards, and these models do not see a benefit from matched RAM sticks.
     
  20. ready2switch macrumors 6502

    Joined:
    Apr 7, 2006
    #20
    While some PC manufacturers offer 4GB options, Windows XP (home, media, and pro) only recognizes 3GB (something many people may not know).

    I, too, would be interested to know if the limit for hardware to use 3GB is a restriction of the current boards or a firmware issue. Not that I really need 4GB now, but being currently limited by my computer (really old Dell that will only recognize 768meg), I don't want to spend money on a new machine with such a low ceiling of upgradability.

    Originally I intended to buy when my finances will allow, but the more I consider the boat I am in now (and my unwillingness to be there again), the more I think I will wait until this particular issue is resolved, be it with the Santa Rosa platform (if that will indeed resolve it) or some type of firmware update. Luckily, I am buying for "want" and not "need", so I can afford the time spent waiting.
     
  21. da5id macrumors newbie

    Joined:
    Oct 12, 2006
    #21
    It would be nice to see it ran with a C2D 2GB vs 3GB.
     
  22. suneohair macrumors 68020

    suneohair

    Joined:
    Aug 27, 2006
    #22
    If you are wondering why the iMac and MBP has a 3GB ceiling, it is a cost issue.

    2GB so-dimms are not cheap. I believe that 4GB will work on the CD iMacs as well as MBP/MB. It is just so expensive to fit one with 2 2GB so-dimms. Maybe Apple wanted to give more options, but as you can see the 3GB upgrade is not cheap.

    There is no hardware or software limit on a Mac with OS X, it is a matter of cost that Apple is not offering 4GB. I challenge someone to buy 2 2GB dimms and give it shot. I bet it will work.
     
  23. Eidorian macrumors Penryn

    Eidorian

    Joined:
    Mar 23, 2005
    Location:
    Indianapolis
    #23
    Yeah, I know that you need identical sticks for dual channel. CPU-Z seems to keep reporting my 1.5 GB of RAM as being in Dual and not single. I do the same thing on my other PC's here and it reverts to single channel.
     
  24. CanadaRAM macrumors G5

    CanadaRAM

    Joined:
    Oct 11, 2004
    Location:
    On the Left Coast - Victoria BC Canada
    #24
    It has been tried. (article on arstechnica) a single 2 Gb module does run in a MB CoreDuo. Any combination of 2 + another module fails to boot. So you're no further ahead than 2 x 1 Gb SODIMMs

    Apple quite explicitly says that you can install 2 x 2 Gb into a C2D Mac, but only 3 Gb will be recognized, not 4.

    It is not a cost-of-chips issue.

    Reply to other posts above: Dual channel access is implemented in all of the intel Macs when two matching modules are installed - it is not limited to the integrated video machines. You may argue what the net, real-world benefit of it is in different machines, but it is still active.

    Dual channel access requires 2 RAM modules of the same speed, size and composition.
     
  25. TBi macrumors 68030

    TBi

    Joined:
    Jul 26, 2005
    Location:
    Ireland
    #25
    You don't need identical sticks, just two. Then again that could be only with AMD processors.
     

Share This Page