Can the old DDR2-667 SODIMM work with the new iMac?

Discussion in 'iMac' started by jameszhu, Apr 28, 2008.

  1. jameszhu macrumors newbie

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    Apr 28, 2008
    #1
    New iMac is shipping with DDR2-800 SODIMM,
    But I have 4G DDR2-677 SODIMM, can I use them on the new iMac?
     
  2. Eidorian macrumors Penryn

    Eidorian

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    #2
    It's a crap shoot. The Montevina platform does support DDR2-667 RAM. You can try using it but that's no guarantee.
     
  3. jameszhu thread starter macrumors newbie

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    Apr 28, 2008
    #3
    Will the old DDR2-667 memory slow down the system (significantly?), if it works with the new iMac

    thanks
     
  4. Muncher macrumors 65816

    Muncher

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    #4
    It would result in a marginal decrease in performance. You do have 2 paired 2GB sticks though (right?), which would enable your imac's dual channel function, that should offset the performance decrease.
     
  5. D4F Guest

    D4F

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    #5
    Can somebody clarify this?
    I mean tested/working/not working and etc...
     
  6. Eidorian macrumors Penryn

    Eidorian

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    #6
  7. iGrant macrumors 6502a

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    #7
    No you can not use DDR2-677 SODIMM ram in a Motherboard that requires DDR2-800 SODIMM memory. You computer will not boot period.

    However you can use DDR2-800 SODIMM memory in a motherboard designed for DDR-677 SODIMM. The Ram can slow *itself* down to meet the requirements for the motherboard but not the other way around.

    *UPDATE*

    I have never seen that before ever. I know you can put faster spec ram into a slower spec motherboard, but I have never seen it work the other way around never.

    -iGrant
     
  8. Eidorian macrumors Penryn

    Eidorian

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    #8
    Chipsets can support a wide variety of RAM speeds nowadays regardless of their frontside bus.
     
  9. iGrant macrumors 6502a

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    #9
    Like I said in my earlier post, I have never seen that before. I think that is awesome, but its just not something I am use to seeing. WOW

    -iGrant
     
  10. CanadaRAM macrumors G5

    CanadaRAM

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    #10
    While dual channel operation results in a 6% - 8% improvement in real world terms, you should be comparing dual channel 667 MHz to dual channel 800 MHz -- and there's no escaping that the 667 MHz RAM is running at a 16% lower speed.
     
  11. hank-b macrumors member

    hank-b

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    Apr 29, 2008
    #11
    Slight off-topic - will faster memory than specified work?

    That's interesting - I have a G4/800MHz iMac which takes PC133 SODIMM or SDRAM. Someone I work with has got some surplus PC2700 SDRAM memory going free, so do you think this would this work in my G4?

    HB
     
  12. iGrant macrumors 6502a

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    #12
    It being a G4, you have to make sure of three things, first being that the memory is built using low density chips and secondly that the ram has the sam pin connection as the motherboard and third that it is not beyond the hard ware limit for recognizing memory. For example you can not put 3gb in a Power Mac G4, just 1.5gb depending on the model you have you will either have 3 or 4 slots for ram.

    -iGrant
     
  13. JasonElise1983 macrumors 6502a

    JasonElise1983

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    #13
    no...those to RAM chips are not compatible. PC2700 is DDR SDRAM and PC133 is just SDRAM. Sorry...but i believe that is a no go. But i may have some PC133 lying around somewhere.

    -JE
     
  14. Pressure macrumors 68040

    Pressure

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    #14
    Yes, it is backwards compatible.

    You can use 667Mhz DDR2 SODIMMs in the new iMac.

    If you couple slower ram with faster ram, the faster ram will slow down to the slowest ram.
     

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