Ram upgrade: DDR2 667MHz to 800MHz?

Discussion in 'MacBook' started by 3paulx, Feb 16, 2011.

  1. macrumors member

    Joined:
    Feb 5, 2009
    #1
    Hi, im planning change my white MacBook's ram from DDR2 2gb to 4gb but the stock Ram is 667MHz and I might replace it with DDR2 4gb 800MHz from a Macbook Pro.....is that ok? any problems/complications with peroformance if i do that? Thanks!

    Peace!
     
  2. Contributor

    AndyK

    Joined:
    Jan 10, 2008
    #2
    http://www.crucial.com/

    Use their memory scanner & it'll tell you what the best upgrade choices are for your machine.
     
  3. macrumors member

    AF08

    Joined:
    Jun 20, 2010
    Location:
    Huntington Beach
    #3
    should work

    the 800mhz ram will slow down to 667mhz ;)
     
  4. macrumors 65816

    logana

    Joined:
    Feb 4, 2006
    Location:
    Scotland
    #4
    Not quite correct - the later nVidea white MacBooks have a higher bus speed and can run the 800MHz at that speed although Apple fitted some with the slower PC5300 ram.

    But we don't know what MacBook AF08 has....
     
  5. macrumors 6502a

    blackburn

    Joined:
    Feb 16, 2010
    Location:
    Where Judas lost it's boots.
    #5
    Macs with 667 pre-fitted in them will refuse to boot with 800 MHz ram.
    It's due to the spd in the ram modules. (It boots only if one is 667)
    There is a speed table that can only carry 3 different speeds (JDEC ddr2 offical spec), so let me explain:

    The 667 module has 400 - 533 and 667 programmed in it.

    But the 800 module has 400 - 533 - 800, so when the macbook checks for the 667 speed and doesnt find it, it wont boot.
     
  6. macrumors 65816

    logana

    Joined:
    Feb 4, 2006
    Location:
    Scotland
    #6
    That cannot be right either - I spent yesterday checking some 2GB PC6400 ram modules. I was using a MacBook 2,1 (2GHz Core 2 originally fitted with PC5300 ram). The MacBook booted fine with a single PC6400 module (800MHz) and the memory tested fine and System Profiler reported it as 667MHz DDR2......

    The MacBook 3,1 and 4,1 models (late 2007 to 2008) won't boot with a single PC6400 chip in them but the MacBook 5,2 (nVidea white non-unibody) will.
     
  7. thread starter macrumors member

    Joined:
    Feb 5, 2009
    #7
    thanks for the reply guys! :D
     
  8. macrumors 6502a

    blackburn

    Joined:
    Feb 16, 2010
    Location:
    Where Judas lost it's boots.
    #8
    Well i don't own any of these macbooks, just what I've read. Since my unibody works with faster ram but overheats, It must be on model by model basis. (I don't know if there is an table/post with that usefull information)
     

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