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AndrewB43 Author

Level 1

8 points

iMac 9,1 - Mid 2009 accepting multiple types of RAM?

I own a Mid 2009 iMac (Education Edition model) that supports up to 8GB of RAM at 1066MHz and PC3-8500. I purchased it over a year ago from eBay and don't use it for very much (a bit of work here and there), but decided to upgrade the RAM from 4GB to 8GB.

On further inspection, I noticed that the 2x 2GB modules inside were actually 1333MHz PC3-10600 versions, which are only supported on 2010 - 2011 iMacs. I added two 4GB sticks at 1066MHz and they worked fine. Could anyone suggest why the iMac accepted the 1333MHz sticks despite not being officially supported by Apple? It's not a problem, but just strange!

Posted on Jul 14, 2020 11:41 AM

Top-ranking reply

Kappy

Level 10

361,879 points

Posted on Jul 14, 2020 11:54 AM

Because in this case, there is no difference in the faster RAM except the speed rating. The actual RAM speed is determined by the computer system's bus. At the time the RAM was installed, it may be that slower rated RAM of the same type was hard to find. You will have to find two 4GB modules meeting the PC3-8500 requirement, but you could use 1333MHz modules, if you cannot find any rated at 1066MHz. It's not a problem nor strange.

What Apple states as "officially supported" means, at the time of manufacture this is what was available and passed our testing.

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iMac 9,1 - Mid 2009 accepting multiple types of RAM?

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