Which RAM of these 2?

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I want to add 4 GB of RAM memory to my iMac mid-2011 i5 21.5".

What's the difference between these two? (Results from Corsair's memory finder tool.)



Corsair Mac Memory — 4GB DDR3 SODIMM Memory Kit (CMSA4GX3M1A1333C9) single stick

Corsair Mac Memory — 4GB Dual Channel DDR3 SODIMM Memory Kit (CMSA4GX3M1A1066C7) single stick



Difference I see is 9-9-9-2-4 or 7-7-7-2-0 between the two, repectively; what do these figures mean?


Also, is there any advantage to having 1 stick of 4 GB vs. 2 sticks of 2 GBs?
 

pigoo3

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Purchase from OWC or Crucial…it's much easier!:)

- OWC
- Crucial

- Nick
 

Raz0rEdge

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OWC sells memory especially for Macs and they list the following options for your iMac..

Looking at the specifics, the memory has CL: CAS 9-9-9-24, so the Corsair memory you found that matches these Cas/Latency settings would be the one that I would recommend..
 

bobtomay

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Plus one of them is 1333Mhz and one is 1066Mhz.

Your iMac uses 1333Mhz memory, aka PC3 10600 DDR3 SO-Dimms.

OWC or Crucial are much easier.
 

pigoo3

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(Wow, memory sure is cheap these days!)

Depends what computer the ram is for. 4gig (2 x 2gig) for your iMac is $21.99…4gig (2 x 2gig) for my MacBook is $55.97.:(

Sounds like you found what you needed…congrats!:)

- Nick
 
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Got my RAM in (added 4 to the 4). As expected, no change in speed but with only 7 tabs running (of ordinary websites) this thing is consuming 5Gs of it. I don't know where it's all going. Now I wish I had gone for more (almost).
 

pigoo3

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Got my RAM in (added 4 to the 4). As expected, no change in speed but with only 7 tabs running (of ordinary websites) this thing is consuming 5Gs of it. I don't know where it's all going. Now I wish I had gone for more (almost).

Adding ram to a computer does not always result in any sort of speed increases. You had 4gig of ram to begin with (which really is not all that bad). If you only had 1 or 2 gig of ram...and went to 4 or 8gig...then you would probably have seen more of a performance increase (snappiness).

In the average users case...going from 4 gig to 8gig of ram simply helps to insure that no single application is "starved" for ram. And with 8gig of ram...you can open more apps...with less of a chance of a decrease in performance.

- Nick
 
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I've noticed that it now devotes much more space to "inactive". So with 3 website tabs running, and after surfing all day, 3.74 is inactive. As I understand it, it holds in memory pages I might re-visit. This is unique to Macs I assume.
 

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