iMac won't boot with 4GB but will with 3GB—but I think I can have 4GB...

Discussion in 'Mac Basics and Help' started by collegeisamovie, Apr 7, 2009.

  1. collegeisamovie macrumors newbie

    Joined:
    Apr 7, 2009
    #1
    When I look at "About This Mac" it says that I have a 2.4 GHz Intel Core 2 Duo. I originally had two 1GB sticks. When I installed two 2GB RAM sticks, it wouldn't boot. Just for fun, I tried putting one 2GB and one 1GB stick inside, and it boots fine.

    crucial.com says that I can have up to 4GB: http://www.crucial.com/uk/store/listparts.aspx?model=iMac 2.4GHz Intel Core 2 Duo (20-inch - 667MHz)

    But the guides say that it depends on if I have Merom w/ Santa Rosa chipset or not:
    http://guides.macrumors.com/Understanding_Intel_Mac_RAM

    But I read somewhere else that even if I install two 2GB sticks that it will just ignore the power of the second one and default to 3GB.

    Any help anyone can provide would be great. I'm fairly new at this sort of thing.
     
  2. BlueRevolution macrumors 603

    BlueRevolution

    Joined:
    Jul 26, 2004
    Location:
    Montreal, QC
    #2
    Apple says it supports up to 4 GB too.

    Have you tried each of the 2 GB sticks in that configuration? It could be that one is faulty.
     
  3. DoFoT9 macrumors P6

    DoFoT9

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    #3
    can you please provide some more information about your computer!!

    we cant work with "2.4GHz Core 2 Duo". we need more, what type of CPU is it? what is the FSB of the machine?? etcetcetc
     
  4. collegeisamovie thread starter macrumors newbie

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    Apr 7, 2009
    #4
    @BlueRevolution—I will try that now and let you know.

    Here's my hardware overview:

    [​IMG]
     
  5. Cave Man macrumors 604

    Cave Man

    #5
    One of your 2 gb sticks is bad or it was improperly seated.
     
  6. collegeisamovie thread starter macrumors newbie

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    Apr 7, 2009
    #6
    I tried swapping out one of the 2GB sticks for the other. They both work with the other slot being occupied with a 1GB stick. I'm going to try one more time to place both 2GB sticks in. I'll be back in a minute to let you know what happens.

    Thanks guys.
     
  7. Cave Man macrumors 604

    Cave Man

    #7
    You have a Santa Rosa iMac. It can take up to 6 gb of RAM. Only the Calistoga Macs (iMac, MacBook, Mini, MacBook Pro) were limited to 3.2 gb RAM (with Core 2 Duo) or 2 gb RAM (with Core Duo/Core Solo). Make sure you seat them properly. Also, are they identical chips?
     
  8. BlueRevolution macrumors 603

    BlueRevolution

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    #8
    Wait, so my iMac8,1 can support 6 GB too? Apple says the limit for all of them is 4, and I hadn't thought to check if they were underselling. Also, side note – are you seriously from Neander Valley, or is that just to suit your username?
     
  9. Cave Man macrumors 604

    Cave Man

    #9
    If it's SR, it'll take 6 gb. I have it in my SR MPB.

    Why, sure! ;)
     
  10. DoFoT9 macrumors P6

    DoFoT9

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    #10
    what are the limits of a Penryn iMac then?? currently it sits at 4GB...
     
  11. Cave Man macrumors 604

    Cave Man

    #11
    Penryn's a cpu series, not chipset. It's found in the SR and 9400m iMacs and can take 6 or 8 gb, respectively, IIRC.
     
  12. collegeisamovie thread starter macrumors newbie

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    Apr 7, 2009
    #12
    I'm pretty sure I seated them properly. I tried swapping both 2GB out and putting 1GBs in their place. It booted fine. With both 2GB sticks in, the computer turns on, but doesn't have the startup noise and the monitor stays powered off.

    Any ideas? They are identical Kingston 2GB sticks. Again, they both work as long as there is a 1GB and a 2GB in there.
     
  13. Cave Man macrumors 604

    Cave Man

    #13
    OK, so here's the deal. There's only one Intel iMac series that won't boot with more than 2 gb RAM, and that's the Core Duo Calistoga-based iMacs. The Core 2 Duo iMacs (Calistoga, Santa Rosa and 9400m) will all boot with 4 gb of RAM. The Calistoga series will only address 3.2 gb or so, while the others will see all 4 gb. So, there's something amiss with your SO-DIMMs if yours is not booting. Can you get another 2 gb stick to try?
     
  14. DoFoT9 macrumors P6

    DoFoT9

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    #14
    that it is, so it still uses the SR chipset then doesnt it. hmmm 6GB is pretty interesting.
     
  15. flopticalcube macrumors G4

    flopticalcube

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    #15
    Could it a fault with his memory controller?
     
  16. DoFoT9 macrumors P6

    DoFoT9

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    #16
    it worked with 2x1GB sticks... i dont see why the 2x2GB sticks wouldnt work unless the sticks are faulty themselves (which have been tested anyway).. wierd.
     
  17. collegeisamovie thread starter macrumors newbie

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    Apr 7, 2009
    #17
    How can this be possible if both of the 2GB sticks work with the other 1GB stick?

    Also, I tried using 800 MHz sticks earlier today and they wouldn't work (didn't think to try a 1GB stick with them, so not sure if that would have worked). So I assumed that, after reading some info, I had to use 667 MHz, even though the guy at the store said that 800 MHz would down-convert or something to 667 MHz.

    So, if that is true and 800 down-converts to 667 MHz then I have already tried two other 2 GB sticks and they didn't work either.
     
  18. DoFoT9 macrumors P6

    DoFoT9

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    #18
    thats correct, 800MHz would "convert down"
     
  19. collegeisamovie thread starter macrumors newbie

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    Apr 7, 2009
    #19
    Pardon the awkward phrasing :)

    So, if this is the case, then I've definitely tried out four different 2GB sticks. No combination of both slots being filled with 2GB sticks work. The only combination that works is one 1GB stick and one 2GB stick.

    I guess I'm stuck unless anyone else has any ideas. 3GBs are better than 2GBs.
     
  20. DoFoT9 macrumors P6

    DoFoT9

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    #20
    haha thats ok!!

    its very odd!! are you running the latest version OS of Leopard and stuff??
     
  21. Cave Man macrumors 604

    Cave Man

    #21
    If the SO-DIMMs are the same and also incorrect, they will cause a problem if they are incompatible. If one of these is installed with a "correct" SO-DIMM that forces the 2 gb to "step down" to its level, it might work. Can you provide a link to these 2 gb sticks so we can see the details of their specifications?
     
  22. collegeisamovie thread starter macrumors newbie

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    Apr 7, 2009
    #22
    At this point I swapped out the 800 MHz RAM for the 677 because, at the time, I didn't know they would step down.

    Here's a link: http://www.bestbuy.com/site/olspage.jsp?skuId=8669602&type=product&id=1196470791607
     
  23. collegeisamovie thread starter macrumors newbie

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    Apr 7, 2009
    #23
    Sure am. 10.5.6.
     
  24. DoFoT9 macrumors P6

    DoFoT9

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    #24
    ok then well it rules that out.. do you have any access to Windows via Bootcamp?? could be worth testing with that...
     
  25. collegeisamovie thread starter macrumors newbie

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    Apr 7, 2009
    #25
    Yes, but what would I test? When I try to boot up my computer it doesn't even get to the screen where I'd switch into Windows. It just stays black.
     

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