8 Replies Latest reply: Mar 30, 2011 1:50 PM by Teufelhunden
BreizhRonB Level 1 (0 points)
I have some memory modules left over from various upgrades and I would like to use them to upgrade my daughter's iMac which is a 2.0 GHz machine using 667 MHz DDR2 SDRAM PC2-5300. I have 1 Gb of that memory from wife's iMac which is the same model but I also have 1Gb of 800 MHz DDR2 SDRAM 6400 from my own 2.4 GHz iMac. Can I install them together in my daughter's machine? If I can't mix them, will the 800 MHz run in it on it's own and would there be any benefit?

I also have some 667 MHz 5300 from my laptop which appears to be the same as that in the 2.0 GHz iMac. Can anybody confirm that? Finally, is there any risk in trying any of the above?

Thanks in advance


iMac 2.4 GHz Intel Core 2 Duo, Macbook 2.4GHz Intel Core 2 Duo, Mac OS X (10.6.4)
  • Level 8 (41,760 points)
    Hi Ron,

    Simple answer is NO you cannot mix modules. iMacs are notoriously sensitive to their memory...must match the specified memory in rating, though not size. You can see more about the memory limits at:


    Mixing speed and memory chip classes does not work with Macs.

    You cannot put the 800 in place of 667 as the machine will not start, or if it does will have kernel panics.

    The laptop modules should work, you can try and see.

    Hope this helps.

    Message was edited by: Ralph Landry1
  • Dah•veed Level 7 (33,655 points)
    Finally, is there any risk in trying any of the above?

    Usually if the Mac cannot use the RAM it just does not pass the Power-On Self-Test, you do not hear the startup chime (your sign it failed the test) and the Mac does not startup.

    Or it starts up, experiences a kernel panic and shuts back down.


  • BreizhRonB Level 1 (0 points)
    Thanks Ralph, helps a lot.
  • Dah•veed Level 7 (33,655 points)
    Thank You for extending the courtesy of awarding to comments that are helpful or provide answers in the Apple Discussions, as this is not mandatory, but it is much appreciated!
  • Level 8 (41,760 points)
    You're very welcome, and thanks for the positive feedback, we all appreciate it.
  • Teufelhunden Level 1 (5 points)
    I am buying my first iMac, 27 quadcore, I want to upgrade the memory and ive been reading an immense number of reports on problems with memory configurations. Is there a simple answer? I want at least 8gb, 16gb would be very nice. Can someone direct me to the best choice for memory configurations? 12 gb vs 16gb? brand? I am simply leaning towards getting 12 gb from newegg to avoid the 16 gb issue.
  • rkaufmann87 Level 9 (55,223 points)

    Hi I know you're new so let me try to educate you a little. First is trying to ask a question in someone else's thread is considered rude, it's called thread jacking. I'm sure that wasn't your intent though. Next is if you see a green star by a thread that indicates it has been answered so posting a question in a thread that has already been answered probably isn't even going to be looked at.

    I would recommend opening your own thread and I'm sure you will get some people more than willing to answer your question. If I see it I'll help you too! If you need assistance on how to create a thread click above where it says "Expanding your Intel-based iMac" and then you will see a link called *Post new Topic*.


  • Teufelhunden Level 1 (5 points)