Can iMac's RAM be upgraded?

[Mark F]

My iMac is about 3.5 years old. I ordered it with the maximum RAM that was then available for that machine- 4gigs. Apple told me that was the max the machine could take. I'm happy with the machine but would really love to increase the RAM. DOes anyone know if there is a way to go beyond the 4 gigs? I run Snow Leopard.

THanks.

[Walter_temp]

3.5 years doesn't sound good. Take a closer look and compare with the table in
http://en.wikipedia.org/wiki/IMac_%28Intel-based%29#Aluminum_iMac

Ciao, Walter

[Gemmtech]

The maximum amount of ram that machine can address is 4GB, I had forgot about that when I installed 8GB, the machine shows 4GB.

[Mark F]

thanks. I was afraid of that.

[JBerardi]

OWC says you can get six gigs in there, and they do actually test this stuff:

http://eshop.macsales.com/shop/apple/memory/iMac

http://eshop.macsales.com/memory/OWC_Test_Lab

I would assume Gemmtech's 8 gigs didn't work because it maxes out at six, so when you put two four gig sticks in there, it ignores one of them.

[Gemmtech]

It was NEVER a ram or MAC OS issue, it was a IMac hardware issue, and actually when you install 4GB it shows up as 3GB and if I remember correctly they should be matched sticks.  I don't buy IMacs anymore and the latest don't suffer from that limitation.  I believe there was an EFI update that one could do to their macbook.

[JBerardi]

It was NEVER a ram or MAC OS issue, it was a IMac hardware issue, and actually when you install 4GB it shows up as 3GB and if I remember correctly they should be matched sticks.  I don't buy IMacs anymore and the latest don't suffer from that limitation.  I believe there was an EFI update that one could do to their macbook.

Officially yes... but actually no:

Earlier iMac models, both iMac 2007 and iMac 2008 can be upgraded to 6GB due to the fact that they use the same chipset (Santa Rosa) used in the latest Macs officially certified for 8GB.

This wasn’t known at the time these machines came out as there were no 4GB memory sticks available at the time. If you wonder if perhaps 2 x 4 GB memory sticks for the total of 8GB can be installed in your iMac 2007 or 2008 to 8GB – the machine will report 8GB available, but this will NOT work as the system will freeze and crash – therefore 8GB in iMac 2007 and 2008 is highly UNSTABLE (this is just the way it is, the motherboard was not engineered with 8GB in mind for these models).

6GB is the unofficial maximum that can work well and be stable on both iMac 2007 and 2008, including all unibody laptops certified originally for 4GB – confirmed by actual users in several Mac community forums (if you google it there are lots of pages on it).

http://www.maconsteroids.com/blog/imac-2007-2008-6gb-ram-upgrade/

I upgraded my MBP (pre-unibody) to the unofficially supported 2gb + 4gb combo a couple years back, works just fine.

[Gemmtech]

You installed it in a MBP and it has been well documented that you can do that.  The fact is that even the IMac I installed 4GB it only shows up as 3+GB, I can't remember the exact amount, like 3.3GB.  The other issue is there is a performance hit when the ram sticks aren't matched.  I did google it at the time, but as it stands the 4GB (2+2) is showing up as 3GB.  That article doesn't even address the match stick performance hit.  At the time we tried several different brands of ram, they had all worked fine, however they all reported 3GB.  It's hard to believe that 6GB shows up as 6GB when 4GB shows up as 3GB and that issue is well documented and it is how I first came to learn of the 4GB limit 3GB useable.  Ram is cheap, buy 6GB and stick it in, see what happens...  I will admit, I have never attempted to install 6GB into an one of the mentioned IMacs, however the 4GB does work fine, it just shows as 3GB.