Can the late 2009 iMac 27" run 2x8GB DIMM RAM modules?

sparkie7

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Oct 17, 2008
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I have a iMac 27" 2.8 core i7.

Can I install 2x 8GB (DDR3-1066 - 1066Mhz - 1067Mhz - PC3-8500) DIMMS = 16GB?

Or do I have to do an EFI update, and boot to 64bit mode? or is this only required if I were to run 32GB RAM?

Can anyone confirm? TIA
 

redheeler

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Oct 17, 2014
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That RAM should work fine in your iMac. As for 64-bit mode, that's not something you need to worry about if you're running any OS X version newer than 10.6.8.
 

sparkie7

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Oct 17, 2008
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That RAM should work fine in your iMac. As for 64-bit mode, that's not something you need to worry about if you're running any OS X version newer than 10.6.8.
I'm running 10.6.8 currently. Is this sufficient or do I need to install a newer OS?

How about an EFI patch? Do I need to update the EFI if running 10.6.8 to run 16GB using 2x8GB RAM?

Just to clarify, Apple states 4GB per slot. Can it handle 8GB per slot?
 
Last edited:

redheeler

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Oct 17, 2014
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I'm running 10.6.8 currently. Is this sufficient or do I need to install a newer OS?

How about an EFI patch? Do I need to update the EFI if running 10.6.8 to run 16GB using 2x8GB RAM?
Ah, well in that case you still don't need to worry, as it should not affect the amount of RAM usable by your system. https://www.cnet.com/news/64-bit-snow-leopard-defaults-to-32-bit-kernel/

Interesting to see someone still running Snow Leopard on a 27" iMac as it is getting to be old/insecure, but regardless it should have no problem using the extra RAM.
 

nambuccaheadsau

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Oct 19, 2007
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If you choose to you can run up to 4 x 8GB modules and it is a matter of simply popping them in. Just ensure you get Mac compatible memory modules, nothing from a PC shop or eBay. Be aware Snow Leopard has not been supportyed by Apple for some years, no more Security Updates, Safari Updates etc. If you do online banking I think you will shortly run into problems with lack of security. Have a read of this from OWC Mac specialists:-


https://eshop.macsales.com/shop/memory/iMac/DDR3_21.5_27