Which RAM?

Discussion in 'Mac Basics and Help' started by jmufellow, Aug 12, 2008.

  1. jmufellow macrumors regular

    Joined:
    Jun 17, 2005
    #1
    I am wanting to buy RAM for my aluminum iMac 2.4GHz 20 inch screen. However, there are two options that match the above specs. The only difference between the two is that one says:

    Aluminum Intel Core 2 Duo iMac 2.4GHz 20" Widescreen (200 Pin PC2-5300 DDR2 SODIMMs)

    And the other says:
    Aluminum Intel Core 2 Duo iMac 2.4GHz 20" Widescreen (200 Pin PC2-5300 DDR2 SODIMMs)

    What is the difference between "200 Pin PC2-5300 DDR2 SODIMMs" and "200 Pin PC2-5300 DDR2 SODIMMs"??? I'm so confused. If you are wondering what RAM site I'm getting this information here's the link: data memory systems Thanks for any and all help!
     
  2. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #3
    You're quoting two exactly identical specifications. There is no difference.

    If you have questions that these sources doesn't cover, you can check to see if it has been answered in another thread by doing a Google search of the forums. I hope this helps!
     
  3. jmufellow thread starter macrumors regular

    Joined:
    Jun 17, 2005
    #4
    Oops. How embarrassing.:eek: I messed up my copy and pasting. Here are the two configurations that I intended to copy:

    Aluminum Intel Core 2 Duo iMac 2.4GHz 20" Widescreen (200 Pin PC2-5300 DDR2 SODIMMs)

    Aluminum Intel Core 2 Duo iMac 2.4GHz 20" Widescreen (200 Pin PC2-6400 DDR2 SODIMMs)

    So, what I meant to ask is what is the difference between "200 Pin PC2-5300 DDR2 SODIMMs" and "200 Pin PC2-6400 DDR2 SODIMMs"? In the mean time I'll look through the information provided above, but if anyone knows the difference between the two, you help would be much appreciated.
     
  4. SaSaSushi macrumors 68040

    SaSaSushi

    Joined:
    Aug 8, 2007
    Location:
    Takamatsu, Japan
    #5
    The PC2-6400 is faster (800MHz as opposed to 667MHz). Only the most recent aluminum iMac revision (early-2008) is compatible with PC2-6400. You should be able to use PC2-5300 (however no guarantees it will work) as well in the newest iMacs but you won't be maximizing it's memory speed potential.
     
  5. SnowLeopard2008 macrumors 604

    SnowLeopard2008

    Joined:
    Jul 4, 2008
    Location:
    Silicon Valley
    #6
    its ok everyone makes mistakes. the higher the PC-XXXX number, the faster the bus speed. older speeds are compatible but you wont use the max potential. like me driving a 4WD car on a freeway, im not using the maximum 4WD since freeways are straight..
     
  6. Makosuke macrumors 603

    Joined:
    Aug 15, 2001
    Location:
    The Cool Part of CA, USA
    #7
    I'm not sure if this is what you meant or not, but it sounds like you're saying that PC2-6400 won't work in an older iMac that requires PC2-5300. What I'm pretty sure is the case is that only the newest iMacs require PC2-6400; older ones should be compatible with it, they'll just not run it at full speed.

    At least in the past, a computer requires a minimum RAM speed, and will be compatible with anything at or above that speed in the same form factor.

    For example, an ancient computer that required PC66 can also use PC100 or PC133, but if PC133 is necessary PC100 won't work at all. Same holds for various speeds of DDR, DDR2, and now DDR3, unless something has changed; if the computer requires PC2-5300 (which is DDR2 form factor), it should run just fine with PC2-6400. If, however, PC2-6400 is required, PC2-5300 won't work (too slow).

    I note this because at work I tend to buy faster RAM than is necessary, so that if we later upgrade to something with slightly higher requirements I can move the RAM if necessary.
     
  7. SaSaSushi macrumors 68040

    SaSaSushi

    Joined:
    Aug 8, 2007
    Location:
    Takamatsu, Japan
    #8
    Check out this recent thread on the topic. CanadaRam is a regular contributor to these forums and sells RAM for a living. I defer to his expertise on the matter. ;)

    Refer also to the Intel MAC RAM Guide and in particular this information:

    The 667 MHz memory bus machines do not benefit from 800 MHz SODIMMs. This is a hardware limitation of the memory controller on the motherboard which is hardwired at 667 MHz (even though the Santa Rosa Front Side Bus is 800 MHz, FSB is not the same as the memory bus). There have been reports of 800 MHz SODIMMs failing in Penryn MacBooks and MacBook Pros.
     

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