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24" iMac (Primo 2009) strange RAM upgrade issue

312 Views 9 Replies Latest reply: Mar 5, 2013 1:40 AM by The Heftster RSS
The Heftster Calculating status...
Currently Being Moderated
Mar 1, 2013 5:23 AM

I have a 24" iMac (Primo 2009) at work. I been granted a RAM upgrade by the IT department and have received 2 indentical 4 GB modules.


The 24" iMac (Primo 2009) uses 1066 MHz DDR3 modules and supports up to 8 GB RAM in 2 slots. I have purchased RAM from this source mac-macbook-macpro/#intcmp=searchProvider_SiteSeeker (Corsair Mac Memory so they SHOULD be fine.)


Here's the issue:

  • I had 2x 2GB modules. I have taken both out.
  • I have inserted the new 2x 4GB modules but the machine refuses to boot. It gives off 3 beeps-interval-3 beeps-interval (repeats).
  • I took out one of the 4GB modules from slot B. It boots.
  • I inserted the one I removed in slot B again so we're back at 8GB. same beeps. No boot.
  • I switched the 2 4GB modules from slot A+B around. Now beep-interval-beep-interval (repeats) No boot.
  • I inserted one 4 GB in slot 1, and one of the old 2 GB in slot 2. It boots with 6GB RAM.
  • I inerted only the one that won't boot when in slot B in slot A, beep-interval-beep-interval (repeats) No boot.


OK - so logical deduction tells me one of the new 4GB RAM modules is defective. No matter what configuration, booting fails with that specific module inserted, though there are different beeps. I also know tha both slots work since the machine works with 6 GB RAM (2+4).


So I called Dustin, and since we're a big customer they sent a new moduel for free. But, I have the same isssue with the new module!! What are the chances I have recived 1 working and 2 defective modules? not big right? So my iMac seems fine with the old 2GB modules and one of the new 4 GB modules, but says no to the 2 other 4GB modules.


YES - I have tried resetting PRAM and SMC to no avail. Any clue?

  • BDAqua Level 10 Level 10 (114,800 points)

    Great work/post!


    Does tthe working 6 GB still work if you swap the modules' slots?


    At the Apple Icon at top left>About this Mac, then click on More Info, then click on Hardware> and report this upto but not including the Serial#...


    Hardware Overview:


    Model Name: iMac

    Model Identifier: iMac7,1

    Processor Name: Intel Core 2 Duo

    Processor Speed: 2.4 GHz

    Number Of Processors: 1

    Total Number Of Cores: 2

    L2 Cache: 4 MB

    Memory: 6 GB

    Bus Speed: 800 MHz

    Boot ROM Version: IM71.007A.B03

    SMC Version (system): 1.21f4

  • BDAqua Level 10 Level 10 (114,800 points)
    Currently Being Moderated
    Mar 2, 2013 12:21 PM (in response to The Heftster)

    I'm thinking this might test the slot that it seems so far only work with 2 GB stick.

  • Mike Sombrio Level 6 Level 6 (9,100 points)
    Currently Being Moderated
    Mar 2, 2013 12:33 PM (in response to The Heftster)

    Corsair ram is me of he cheap bargain basement brands that don't work well with Macs. You said that it worked with one of the 4gb chips alone, why I can't explain. The reason it works with one 4gb and one of the original 2gb chips is because the system is for Inc the 4gb chip to run at the same speed as the 2gb chip. You'd be way ahead to return the Corsair ram and purchase from Crucial.

  • Mike Sombrio Level 6 Level 6 (9,100 points)

    Corsair and other bargin brands aren't manufacturered to the same specs that the better brands sold by Crucial and OWC are. Your Mac requires 1066 MhZ ram and some brands label and sell ram that is actually 1080 MhZ or something other than exactly 1066, but they'll label it as 1066. PC's are way less picky than macs about ram so those brands will work fine in a PC. Like I said before as long as you use one of the original sticks that is exactly 1066 the system will sense that and force the corsair to run at that speed also. There are literally hundreds of threads here about those brands of ram causing problems, almost every one of them is solved by buying ram tested and guarenteed to work with that specific Mac from Crucial or OWC.

  • BDAqua Level 10 Level 10 (114,800 points)
    Currently Being Moderated
    Mar 4, 2013 11:25 AM (in response to The Heftster)

    Well, my best guess is the Mac is looking for one fully recognizable module & then setting the question one to that, some RAM that may be "compatible", might not have the SPDIF chip programmed correctly, yet still be capable of adjusting.


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