Why 3Gb memory limit in 20" & 24" iMac's?

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Hi Everyone,

Isn't it optimal to have matched banks of memory?
My 20" iMac came with 2 512Mb SIMMs which were upgraded to two 1Gb SIMMs. Would a third SIMM perform as well as the matched set?

cheers
 
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iMac 20" C2D 2.4 ghz 2gb iMac 20" C2D 2GB 256MB Graphics Macbook C2D 2GB Powermac G4 Dual 450
i believe that the imac can support 4gb (dual 2gb modules)....someone correct me if im wrong
 
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This is straight off the Apple website:

17-inch model with 2.0GHz processor, 20-inch and 24-inch models

* 1GB (2x512MB) of PC2-5300 (667MHz) DDR2 memory
* Two SODIMM slots support up to 3GB
 
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yes they say that, but they also say macbooks can support 2 gb, when its proven they can actually support 3gb.
 
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You can use either 2 x 2GB or 1 x 1GB and 1 x 2GB. But for some reason the max is 3GB. Most standard PCs only address 4GB anyway, the OS can work around it though, you get the option of highmem in Linux.
 
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But for some reason the max is 3GB.

It's the Intel chipset. The C2Ds can only use 3GB before you get what they call memory overlapping (basically things get stored more than once, so why bother with the extra gig if it's just going to be wasted anyway).
i believe that the imac can support 4gb (dual 2gb modules)....someone correct me if im wrong

You are wrong :p
 
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Thanks for the info folks. :)

Question, how many people have 3Gb RAM in their iMac?
 
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Thanks for the info folks. :)

Question, how many people have 3Gb RAM in their iMac?

Not yet, but I will replace the 1GB module with a 2GB soon. My iMac came with 2GB installed and I was expecting 1GB, so I had already planned on buying RAM.

With Linux I managed to edit Canon 5D RAW files on my laptop which only has 512MB. So I would imagine you only need 3GB if you are editing huge files, or need to have a few open at once.
 
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Do you recommend sticking with the same brand of memory?
 

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