I have an iMac 20 inch mid 2007, and I can't figure out from the chart which of the 2 options it is: iMac (20-inch, Mid 2007) iMac7,1 MB199XX/A iMac (20-inch, Mid 2007) iMac7,1 MB200XX/A

What two options? You can install up to 6 GBs in a Mid-2007 iMac.

Hello Kappy;

I have this same machine. When I upgraded the memory I was advised that the maximum recommended was 4GB. This I installed as a balanced 2 x 2GB.

Balance was recommended and as there are only two slots, I cannot see how you can balance 6GB.

Don't get me wrong, I'm far too inexperienced to question your opinion ... but can you clarify your view, just for education.

I upgraded my memory via Crucial who were very very helpful in the process, sending me written instructions relating to my machine.

First, 4 GBs was the Apple recommendation when the machine was released because 4 GB modules were not available for testing. Since it's release it has been found that each slot supports 4 GB modules, but the memory controller on the motherboard only supports 6 GBs of RAM.

Installing RAM in matched pairs enables dual-channel that improves memory speed by around 10%, plus or minus. So, if you need memory more than faster memory speed then install 6 GBs. If more memory isn't an issue but you need better memory speed then install a matched pair.

Big thank you.

71.

You're most welcome.

Please note the items listed under Legend in the right sidebar of this page. 🙂

I always do, Kappy. But in this instance I was not the original poster. Or have I misunderstood something?

No. My error.

Your question was answered in my earlier post.

At the Apple Icon at top left>About this Mac, report OSX version, then click on More Info, then click on Hardware> and report this upto but not including the Serial#...

version 10.7.3

Hardware Overview:

Model Name: iMac

Model Identifier: iMac7,1

Processor Name: Intel Core 2 Duo

Processor Speed: 2.4 GHz

Number Of Processors: 1

Total Number Of Cores: 2

L2 Cache: 4 MB

Memory: 6 GB

Bus Speed: 800 MHz

Boot ROM Version: IM71.007A.B03

SMC Version (system): 1.21f4

On the bottom of your iMac stand, you'll find a label with the serial number printed on it, or from the Apple (?) menu, choose About This Mac. Configure To Order (CTO) models are designated with an asterisk (*). Check the last three characters on the serial number:

http://www.appleology.org/2011/01/how-to-identify-imac-models-from.html

http://en.wikipedia.org/wiki/IMac_(Intel-based)

I think, but do not know, that the latter was simply a Build to Orde model with no significant differences as far as anything goes. 🙂

You asked about RAM upgrades. The answer is correct regardless of the model you have. If you have a different question then please make that clear. It's the model identifier that matters and both the ones you listed have the same model identifier.