Home Forums Hardware Mac Desktops & Notebooks How do you install RAM?

On Macs with 4 RAM slots, AFAIK, the factory installed RAM is in the two left slots (upper & lower left slots).

Were I to install two additional sticks of RAM (of a different size) would it be best to merely put them in the two right slots, or, move one of the left sticks to the right side and then install the new RAM?

Or, does it even matter?

I have heard differing opinions and don’t know enough to draw an informed conclusion.

Unless someone else knows more, I would say that it doesn't make any difference. There is nothing specified in Apple's instructions.

First off, you should determine how much RAM you already have and then check Apple's article on "iMac: Memory specifications and upgrades" (http://support.apple.com/kb/ht3011) to find out how much additional RAM you can actually add – there is a maximum, which is different for different models and configurations.

I also suspect that speed of the memory stick(s) should be the same. If not, then the slower memory will dictate overall performance in that regard (or so it was in older iMac models and those with a PowerPC processor).

Alas, I know not, exactly the iMac model, other than it's 21" iMac and I guess it's 2010 or 2011 vintage. I say that because it has an optical drive and OS 10.8.5 with 4 GB RAM, and has a FW 800 port.

A neighbor is giving it to me tomorrow.

Re the slots for the RAM I hope to get (assuming it's user installable)--

Like Jon says, I suspect that any difference is so minute that only if one had laboratory equipment would he even be able to discern a difference. And even that would have no real world consequence.

System Information (system report in later versions of OS X) will tell you what iMac model you have and what DIMMS you have in each slot. As I recall from my iMacs the banks should be filled in order beginning with Bank 0, Bank 1, Bank 2, and Bank3. Left to Right and Bottom to Top.

For optimum performance, put an emphasis mark on optimum, performance RAM should be installed in matched pairs. Probably not enough difference to be noticeable in every day use, but still a difference.

If you go here and use "Browse by Product" you can probably find the technical specs you need.

Once you know which model iMac you've got, check out Apple's KB article iMac: How to remove or install memory for installation details. Matching DIMM pairs are not required, but never hurt, as joemikeb recommended. That said, the i5 and i7 quadcore models do require both bottom slots to be filled; there is no such requirement for the top slots.

Most vendors indicate that 2011 iMacs can accommodate a maximum of 32GB in RAM (4 x 8GB), twice the amount Apple specs state (4 x 4GB). Mactracker lists a maximum of 32 GB for the 2010 models* as well, but several vendors don't.

*) Contrary to the one I quoted, the latest version of Mactracker (7.3) lists a 16 GB RAM max for the 21.5" 2010 iMac model, but not for the 27" iMac.

The factory installed RAM is in the first bank; install your new RAM in the second bank (the two unused slots). There's no need to move the existing RAM, and for best performance, you shouldn't.

Many, many thanks to all.

Tonight, my newish computer gets delivered, and then the details will become clear. While a new-new computer would be better, I find the present practice of not having user-friendly RAM installation a significant drawback. And the same applies vis-à-vis hard drive replacement (though I think that has been the case with iMacs for many years...

Just out of curiosity, what is the 'necessity' for more RAM, or is it just a 'desire'?

(My mid-2011 21" iMac with 2.5GHz Intel Core i5 processor and 4 GB RAM is vastly more than I seem to need.)


If it's my vintage iMac, then RAM-installation is relatively easy (even though not as much so as with newer models).

My (beloved's) new "old" machine: Late 2009 21.5 " iMac, C2D Model MB950LL, 3.06 GHz, 4 GB RAM, 10.9.1

Me thinks Grelber was smack on when he asked if I need or (merely) want additional RAM. 'Tis the later, I confess, as my frau mainly emails and surfs; no real processing to speak of. Still, I'll hunt about for an additional 8GB...

On the plus side, the machine is in perfect shape, was free, is a bunch faster that its predecessor, and She Who Will Be Obeyed is delighted.

You might want to check out 'conventional wisdom' #5 (‘Adding RAM always improves performance’) in the MacWorld article Fact or fiction: What does (and doesn't) actually speed up your Mac for some details about how and why extra RAM may (or may not) benefit you.

Gads, I just hate it when I find out that what I know to be true, ain't.

Perhaps I'll do DNA sequencing, video rendering, & global weather forecasts/predictions while playing 3D chess...

I will say there is one place where more RAM really, really matters: if you use Parallels or VMware to run Windows at the same time you run Mac OS X.

I upgraded my Macbook Pro from 8 GB to 16 GB of RAM just last week, then started my Windows VM (Windows 7 Home Premium running in Parallels) and ran the Windows Experience Quality benchmark. The performance of the Windows VM nearly doubled with the extra RAM.