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Old May 23, 2013, 03:48 PM   #1
Radiating
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Can you do 3x8GB of RAM?

Can you use 3 x 8gb or 2x 4gb + 2x 8gb with the imac? Will this impact performance at all?

I have an imac high end with 8gb and need at least 20 gb of ram. I was wondering if I could just pop in 2x8gb sticks from crucial or 3x8gb sticks and get full performance. Thanks.

Last edited by Radiating; May 24, 2013 at 01:19 PM.
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Old May 23, 2013, 04:03 PM   #2
martinm0
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Originally Posted by Radiating View Post
Can you use 3 x 8gb or 2x 4gb + 2x 8gb with the imac? Will this impact performance at all?

I have an imac high end with 8gb and need at least 20 gb of ram. I was wondering if I could just pop in 2x8gb stocks from crucial or 3x8gb sticks and get full performance. Thanks.
Not sure about 3x 8GB, but you're good to go with 2x4GB and 2x8GB for 24GB total.
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Old May 23, 2013, 07:17 PM   #3
Canuckfu
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Originally Posted by martinm0 View Post
Not sure about 3x 8GB, but you're good to go with 2x4GB and 2x8GB for 24GB total.
I've been trying 2x8gb and 2x4gb on my mid 2010 11,3 i3 but with no luck
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Old May 23, 2013, 07:37 PM   #4
drambuie
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With 3 x 8GB put two DIMMs in the lower bank, (where the two 4GB modules are now), and the single DIMM in the upper bank. Then the lower 16GB will work in dual channel mode, and the single upper 8GB will work in single channel mode. With this arrangement there will be practically no noticeable impact on performance. Then you could add another 8GB DIMM later for a full 32GB.
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Old May 24, 2013, 09:24 AM   #5
martinm0
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Originally Posted by Canuckfu View Post
I've been trying 2x8gb and 2x4gb on my mid 2010 11,3 i3 but with no luck
Hmm. I did this on a 2011 21.5" and 2012 27" iMac without issue. I guess I'm not sure if there are some limitations to the 2010 models (maybe they don't support 8GB modules?). Will have to do some digging.
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Old May 24, 2013, 05:02 PM   #6
toddzrx
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Originally Posted by Canuckfu View Post
I've been trying 2x8gb and 2x4gb on my mid 2010 11,3 i3 but with no luck
That's because the Core i3 on the 27" won't handle more than 16 (4X4GB); only the upgraded i5 or i7 CPUs will.

Scroll down to the iMac "Core i3" section here:

http://www.everymac.com/systems/by_c...y-of-macs.html
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Old May 24, 2013, 11:29 PM   #7
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Originally Posted by toddzrx View Post
That's because the Core i3 on the 27" won't handle more than 16 (4X4GB); only the upgraded i5 or i7 CPUs will.

Scroll down to the iMac "Core i3" section here:

http://www.everymac.com/systems/by_c...y-of-macs.html
I have a late 2009 iMac 27" i5 2.66GHz. According to apple and crucial I can only have up to 16GB (4x4GB 1067). But EveryMac says 32GB.
http://www.everymac.com/systems/appl...009-specs.html

Is EveryMac reliable? Anyone know why Apple wouldn't state this? Thanks for any insight anyone can provide!
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Old May 24, 2013, 11:55 PM   #8
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Originally Posted by ccapman670 View Post
I have a late 2009 iMac 27" i5 2.66GHz. According to apple and crucial I can only have up to 16GB (4x4GB 1067). But EveryMac says 32GB.
http://www.everymac.com/systems/appl...009-specs.html

Is EveryMac reliable? Anyone know why Apple wouldn't state this? Thanks for any insight anyone can provide!
Yes, everyMac is overall reliable.

Apple states what is available from them, not what is possible, they also say maximum HD on some earlier systems to be like 500 GB for instance but this is complete nonsense, Maximum HD size is only limited by what the OS can see, which is much much higher than 500 GB, it is more like ExaBytes but there are no HD's of that size.
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Old May 25, 2013, 12:14 AM   #9
ccapman670
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Yes, everyMac is overall reliable.

Apple states what is available from them, not what is possible, they also say maximum HD on some earlier systems to be like 500 GB for instance but this is complete nonsense, Maximum HD size is only limited by what the OS can see, which is much much higher than 500 GB, it is more like ExaBytes but there are no HD's of that size.
Thank you for the information! Some of what I read stated people were using 1333MHz 8GB chips as well even though mine supposedly needs 1066. I'm going to order some.
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Old May 26, 2013, 09:05 PM   #10
toddzrx
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Quote:
Originally Posted by justperry View Post
Yes, everyMac is overall reliable.

Apple states what is available from them, not what is possible, they also say maximum HD on some earlier systems to be like 500 GB for instance but this is complete nonsense, Maximum HD size is only limited by what the OS can see, which is much much higher than 500 GB, it is more like ExaBytes but there are no HD's of that size.
Quote:
Originally Posted by ccapman670 View Post
Thank you for the information! Some of what I read stated people were using 1333MHz 8GB chips as well even though mine supposedly needs 1066. I'm going to order some.
As I understand it, Apple locks in the specs (for the device in question) at the time of manufacture, and they don't update them even when new hardware becomes available to consumers. So back in 2009, 8GB RAM sticks weren't available and Apple rightly published a max of 16GB in the iMac.
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Old May 26, 2013, 10:06 PM   #11
justperry
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Originally Posted by toddzrx View Post
As I understand it, Apple locks in the specs (for the device in question) at the time of manufacture, and they don't update them even when new hardware becomes available to consumers. So back in 2009, 8GB RAM sticks weren't available and Apple rightly published a max of 16GB in the iMac.
Yes/No, for instance, apple never uses the biggest HD sizes, so there are bigger ones but they don't say this.
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