iMac early 2008 slowing down


macrumors newbie
Original poster
Sep 20, 2014
Citrus Heights, California USA
Hello, I created an account when I got a used early 2008 iMac. It is a 20" C2D 2.4ghz. You guys helped me upgrade it from 2gb to 4gb of ram. Thank you again for your help.

I am running OSX Mavericks as I have seen how many people didn't like Yosemite.
These days even if all I have open is a browser, usually FireFox or Chrome, after I open a few pages all of my ram is used up and memory clean needs to run and clean things up.

I chose to go to 4gb because that was the official maximum, but I just took a look at the cost of 2 4gb chips and I do not think I want to put more money in an older machine.

Does anyone have any advice on how to reduce the ram use?


macrumors 68020
Jun 13, 2015
According to mactracker, the maximum memory is 6.0 GB, not 4.0 GB. You'll only need one 4 GB SODIMM, keeping one of your 2GB modules and replacing the other. The trouble is, they're no longer manufactured in enough quantities to push down the price...

What's your memory pressure-- green, yellow, or red?


macrumors newbie
Original poster
Sep 20, 2014
Citrus Heights, California USA
It's green right now. I think it uses more with Chrome. I open a few tabs and suddenly memory clean needs to free up ram.

When I did some research 4gb was the official limit, but some people said you could to 6gb. Other people said you needed both so-dimms to be the same capacity, or it would slow things down. I think one guy had 2 4gb so-dimms working. I played it safe and went with 4gb.


macrumors regular
Oct 27, 2013

You should consider installing a SSD (solid state drive) to replace your old spinning HD. All operations that access the SSD or HD (meaning most things we do on computers :)) will be dramatically faster with a SSD. I installed a 500 GB SDD in my wife's early 2009 iMac (2.66 GHz C2D, 24" screen) that has only 4GB of memory, and she is delighted with the speed increase. Like you, I deferred installing more memory (up to 8 GB allowed in this model) because of the cost. As it turns out, we don't even need more memory. She uses mostly the Safari web browser, with occasional use of Firefox, so I can't address the issues with Chrome.

OWC ( has excellent video tutorials on installing disk drives in Macs, as well as good prices on SSDs. Current prices are $125 for a 240 GB SSD and $222 for 480 GB.

I also installed Yosemite (currently version 10.10.3), which works VERY well on her older iMac as well as my 27" Retina iMac. Many issues that we had with Mavericks (especially with the Mail app) are now resolved with Yosemite. Highly recommended. My wife regularly accesses her Photos library of 23,000+ photos, and this works very well on her old iMac. The new Photos app that comes with Yosemite works much better and faster than the older iPhoto app under Mavericks, especially with larger photo libraries.

Of course you should also delete any apps and browser extensions that you don't need, paying particular attention to apps that automatically launch at startup. Check out this recent article:

I can't remember if the article mentions this, but leaving a web browser running for a while with multiple open tabs will eventually hog memory and CPU use. Many web sites continually load video ads and push data to the browser, eventually resulting in slowdown of the computer. Close tabs and quit the browser periodically.

Trust me, a clean install of Yosemite, installation of a SSD and simple steps like removing undesired startup items and 'intelligent" use of your web browser will do wonders for a 2008-2009 vintage iMac, even with only 4 GB of memory.

One more thing. Your original hard drive in the 2008 Mac is getting a bit long in the tooth. In my opinion, use of a 7 year-old HD is living on borrowed time. It's time to replace the drive, even if it is working now.


macrumors 6502a
Jun 16, 2012
My iMac, even older than yours, slowed down with Yosemite. But apparently El Capitan improves it dramatically, so I'm going to install that when it is released.