Q: Can I add more RAM?

If it's a new model then you can install up to 32 GBs of RAM.

Absolutely... See Here...

Installing RAM

Desktop   http://support.apple.com/kb/ht1423

It is important that you get the Correct and Matching RAM for your Mac...

This is a Reputable Suppler...Where you can also check how much RAM you can update to...

http://www.macsales.com/

Please forgive me if this sounds like a stupid quesion!  I want to buy an iMac, 21 inch with the 2.7GHz i5 processor.  I want 8G of RAM.  Selecting that at the time of purchase adds $200.00 to the cost.  If I buy it separate it's considerably less.  AnaMusic - I followed your link above and found this is what I need:

http://eshop.macsales.com/shop/memory/iMac/2011/DDR3_21.5_27

But what do I buy?  Do I buy the 8G kit and REPLACE what comes with the computer or do I buy the 4G kit and use it in addition to what comes with the computer?  I plan on installing it before even turning the computer on for the first time.

Thanks for your time, and again apologies it this is a dumb question.

Because it is strongly advisable to install memory in identical pairs, you would be best to buy to 2X4 = 8 GB and replace what came in your machine.

If you get everything from Apple, they cover everything under their warranties. If you replace Apple's RAM and add RAM of your own, the onus is on you to figure out that it is the RAM that is malfunctioning later on and deal separately with the RAM vendor.  Also, part of the higher Apple price is for the labor for installing the RAM, which of course you can do yourself with the third party RAM. Apple has directions for replacing the RAM:

http://support.apple.com/kb/HT1423#1

It looks like you need to get the 204 pin chips so that's $130 from the third party versus $200 from Apple. I imagine the third party requires tax and shipping as well. Not sure you're saving all that much, and you have to deal with the details I mentioned above. Maybe not a big deal for some poeple, others might prefer to make Apple fix everything under warranty.

Well if you buy the new model then there is 4 Ram slots available, If you buy it with 4G's of ram already installed two of the slots will most likely be fitted with 2G ram sticks each. So if you buy "two 2G ram sticks" or (The 4G Kit) you'll have ur 8G!

Hope this helps

Thanks Steve - that makes sense.  I would agree with you that the saving from $200 to $130 is not worth the piece of mind of having Apple fit it, but this page shows it to be only $47:

http://eshop.macsales.com/item/OWC/1333DDR3S08S/

It says it's completely compatible with the latest machine, and at over 75% saving I think that probably is worth it?

That is a large savings! Just read the fine print carefully to make sure it is the right RAM for your iMac.If you are comfortable doing this yourself, it seems like a cost saver. Lots of folks have updated their RAM themselves, as Apple has made these machine very accessible.

[FYI, if by some chance you manage to order the wrong RAM, what mostly likely will happen is that your Mac won't start up. At which point, you can always put back in the original RAM and return the other RAM or exchange it for the right chips.]