iMac does not boot (RAM upgrade) - Solid Light, black monitor

Discussion in 'Mac Basics and Help' started by cannonskate, Jun 7, 2008.

  1. cannonskate macrumors newbie

    Joined:
    Jun 7, 2008
    #1
    iMac intel core duo...

    My computer had 1GB of RAM, so I just bought a 2GB RAM card. When I installed both cards together i can hear the hard drive start up and then nothing, no boot up, just a black screen and the "sleep" light is just solid. I know both cards are fine because I tested each by themselves and they both started up and worked well, its only when they are both in at the same time does it do this. also both slots work because i tested both of them! I tried to do the PRAM reset and it doesnt work, and I tried to do it with one card in and then reset and then shutdown and install the 2nd card and still nothing. Please give me some advice, i am soooo frustrated!!
    Thanks!
     
  2. Watabou macrumors 68040

    Watabou

    Joined:
    Feb 10, 2008
    Location:
    United States
    #2
    make sure the ram is properly seated and then try and give it a shot.
     
  3. cannonskate thread starter macrumors newbie

    Joined:
    Jun 7, 2008
    #3
    It is definetly seated properly, I have been trying for hours!

    Right on Watabou, OBAMA IS THE MAN!
     
  4. Watabou macrumors 68040

    Watabou

    Joined:
    Feb 10, 2008
    Location:
    United States
    #4
    Hmm ok. Doesn't seem like it's the iMac problem. Maybe you could try calling the store where you bought your RAM and ask them if you received the correct RAM for your paticular iMac.

    And I love Obama! :D
     
  5. cannonskate thread starter macrumors newbie

    Joined:
    Jun 7, 2008
    #5
    but the thing is that both of the RAM cards work, right now i am using the one i bought, 2GB, and its great, but they only work individually, not together.

    ITS SOOOO WEIRD!
     
  6. Cave Man macrumors 604

    Cave Man

    #6
    You cannot put 4 gigs in a Core Duo iMac (or Mini, MacBook or MacBook Pro for that matter). It is based on the Calistoga chipset, not the Santa Rosa. Two gigs is its maximum.
     
  7. Watabou macrumors 68040

    Watabou

    Joined:
    Feb 10, 2008
    Location:
    United States
    #7
    Ah yeah. I forgot you said yours was a Core Duo iMac. Yeah you can only put 2 Gigs of RAM since the chipset is only 32-bit and cannot support more RAM.
     
  8. Cave Man macrumors 604

    Cave Man

    #8
    Actually, it could take 3 gigs (32 bit addressing) except that Apple, in its infinite wisdom, firmware-restricted their version of Calistoga's memory controller to 2 gigs.
     
  9. cannonskate thread starter macrumors newbie

    Joined:
    Jun 7, 2008
    #9
    im not putting in 4, i am putting in 3Gigs (1GB card+2GB card)....is there any way to unrestrict the firm-ware for the memory controller???

    Thanks guys, seriously I really appreciate the help because I am not very knowledgeable when it comes to computers...
     
  10. Cave Man macrumors 604

    Cave Man

    #10
    Nope, no one has determined how to patch the EFI on the Calistogas. You are stuck at 2x1 gig sticks. Any more and your iMac will not get past the memory check at power-up.
     
  11. cannonskate thread starter macrumors newbie

    Joined:
    Jun 7, 2008
    #11
    THOSE BASTARDS!!!!!

    Well, thank you again Cave Man and Watabou!
     
  12. kennethkearns macrumors newbie

    Joined:
    Jul 18, 2007
    #12
    mine too

    I have gone through exactly the same process as you! iMac will boot with 3 gb but not four. I have a 24 in core 2 duo 2.4 ghz model. Purchased in Feb 2008. According to this http://support.apple.com/kb/HT1423 it should take 4 gb!

    Anyone know anything that could help? It is definitely seated properly and I have tried every combo of chips to see if one was bad and it is not.

    Please Help!
     
  13. GilesM macrumors 6502

    Joined:
    Oct 17, 2008
    #13
    Well, I do not know the answer to your problem, but I can confirm that I am running an iMac purchased in November 2007, with 4GB with no problems.
     
  14. Cave Man macrumors 604

    Cave Man

    #14
    Your problem is different. You have a Santa Rosa iMac, not Calistoga.

    Sounds like you have bad RAM or incorrect RAM. That iMac should take up to 6 gb.
     
  15. kennethkearns macrumors newbie

    Joined:
    Jul 18, 2007
    #15
    I get that my model is different, but this is the closest I have found to my issue.

    the RAM cant be bad because each of the 2 GB modules work when couple with one of the original 1 GB modules (in either bay no less.) They just do not work together.
     
  16. erstwhilepo macrumors member

    Joined:
    Jan 4, 2009
    Location:
    Midwest
    #16
    Could the issue be that he/she is running 2GB in one slot and 1GB in the other? I know on the MacBook, having an odd number of ram is not good for the system and may create problems.
     
  17. keatonprice macrumors newbie

    Joined:
    Jan 18, 2010
    #17
    Did you ever find a solution? I'm having the same problem with my 2008 2.4GHz MacBook. I bought 2x2GB sticks and either one will work in either bay as long as it is paired with one of the old 1GB sticks (Sys Profiler recognizes 3GB shared). But I cannot get the machine to boot up with 2x2GB sticks.
     
  18. Cave Man macrumors 604

    Cave Man

    #18
    Your new RAM chips are incompatible, most likely because of too high of frequency. When you pair it with an OEM chip, the OEM chip forces your new chips down to the proper frequency, thus they work. You need to return your RAM chips and buy a pair that are specific for your model, such as from Other World Computing.
     

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