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Old Aug 7, 2013, 02:26 PM   #1
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Did it take me five years to realize that my iMac is equipped with the wrong RAM?

I have an Early 2008, 2.4 GHz 20" iMac. It still serves me well and I have no reason to replace it or otherwise get rid of it; however, I have 2 GB RAM installed, which is half the maximum allowance for this model. So, I decided to expand the RAM, and started scanning the web for instructions on how to do this. The first piece of information I was able to find was that my model (and make no mistake, this is an early 2008, 2.4 GHz model) runs on 800 MHz DDR2 SDRAM, and that this is what I should be looking for. However, when I opened up About This Mac / System Profiler, the computer told me that it has 2 X 1GB 667 DDR2 SDRAM installed. So, what's going on? Is this a manufacturer's mistake? And what should I do - should I get 667, or 800 for the remaining 2 GB?
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Old Aug 7, 2013, 02:50 PM   #2
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Are you absolutely sure this is a 2008 model? The 2.4ghz C2D iMac was available as a 2007 and 2008 model. Just to verify, in System Profiler, under the "Model Identifier:" field, does it say iMac8,1 or iMac7,1? If it indeed says iMac8,1 then it is definitely a 2008 model and should have 800MHz RAM. If it says iMac7,1 then your iMac is a mid to late 2007 which can only use up to 667MHz RAM.

If you do have an 8,1 I would recommend upgrading fully to the 800mhz ram, you do not want to mix and match 667 along with 800mhz chips inside the same computer, though hey if 667 has been working for you guess you could just buy more of that type, it just won't be operating at maximum efficiency. Though I'm not sure why Apple would have shipped an iMac with the wrong type of RAM. Though if you have a 7,1 iMac then just upgrade by buying more 667 ram, as the 7,1 maxes out at 667MHz.
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Old Aug 7, 2013, 02:56 PM   #3
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That would be quite a mistake if you actually had 667MHz PC2-5300 RAM rather than the 800MHz. I have no direct experience mixing clock speeds of RAM, but I have heard it can be a bad thing to do.

By the way, the (Actual) maximum supported memory is 6.0GB (4+2). Apple usually under-recommends memory, but it should function properly with up to 6.0GB. (both the Early 2008 and the Mid 2007 models)
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Old Aug 7, 2013, 02:59 PM   #4
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So in Hardware Overview des it show iMac 7,1 or 8,1 beside model identifier?

If it is an 8,1 it should have 800 a 7,1 should have 667.

Late 2007 and early 2008 were both 2.4GHz speed. Both also had the same Radeon 2400 or 2600 Pro video cards.

If it were me and I knew it was DDR2 800 then I'd probably just replace it all with 4GB of 800.

Edit: I was typing my response as tag was posting, funny we basically stated the same thing.
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Old Aug 7, 2013, 08:40 PM   #5
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I knew that you guys would question the model. So, once again: System Profiler identifies it as an iMac8,1. BANK 0/DIMM0 has 1GB of 667 MHz and BANK 1/DIMM1 also has 1GB of 667 MHz.

The iMac was purchased directly at an Apple Store in Manhattan.

Hmm, I wonder if this is an individual case, or whether more people were affected. Anyway, I gather that the basic advice is to either buy more of the weaker RAM, or replace it all with 800 MHz, but not to mix the two. Thanks to all three of you for the instant replies.
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