MEMORY UPGRADE ON 2011 iMac: Is it still possible to upgrade my 4GB RAM memory in a mid-2011 iMac?

Save your money. Unless your iMac has a factory solid-state drive, sad history here teaches that any slowness is due to the mechanical hard drive, not a lack of RAM. If the hard drive is the cause, no amount of RAM will help.

A simple test:

• Is the computer slow to start up?
• Are big apps slow to launch?
• Once launched, do those apps seem to respond normally?

Three "yes" answers scream "hard drive."

How about some hard data? I have a Mac with very similar architecture to the entry-level 21.5-inch Mid-2011 iMac including a 2.5ghz i5 processor. It shipped with 4GB RAM. Look at how app launch times were affected as I first doubled the RAM, then replaced the factory mech hard drive for a solid-state drive (SSD):

—Base system as shipped:

4GB RAM and slow SATA 3GBps 5400rpm hard drive: Office 2008 and Photoshop Elements 12 took 15-18 seconds to be ready to use.

—First upgrade, RAM:

8GB RAM and slow SATA 3GBps 5400rpm hard drive: Office and Photoshop Elements took 15-18 seconds to be ready to use.

—Second upgrade, inexpensive solid-state drive

8GB RAM and fast SATA 6GBps SSD: Office and Photoshop Elements take under 4 seconds to be ready to use.

As you see, doubling the RAM did nothing; changing to a fast SSD is what made the difference.

Our 2011 iMac still wears its original HDD but RAM has been upgraded from 4 to 8GB. Still slow, but Activity Monitor shows it is never starved for RAM.

If you want a data-driven eval of your performance and possible ways to improve it in this limited setting, please post a system configuration report. Fortunately there is a safe, secure way to do that without our playing a protracted game of "20 Questions" that could go on for days.

We can quickly and within the limitations of these forums help you determine what issues are at play if you use EtreCheck Pro, available here:

https://etrecheck.com/index

The free version will do nicely for this purpose, although the app is worthy of our financial support.

We can see hard data about drive performance, software issues, and RAM usage. Etrecheck is the development of a long-serving and trusted contributor here expressly for displaying information in these forums to help us help you remotely. It will not reveal any personal or secure information.

Please see this excellent user tip on how to post long text reports like EtreCheck's into a forum response:

How to use the Add Text Feature When Post… - Apple Community

OWC macsales.com sales upgrades for the Mid 2011 iMac's.

see > https://eshop.macsales.com/shop/memory/iMac/2011/DDR3_21.5_27

It can be upgraded to 32GB.

It’s possible, yes. Whether it’s worth it to upgrade a machine that is obsolete is something else entirely.

You do know that adding memory will not speed up the boot time, application and file opening time, right? It only lets you open more files, bigger files.

To speed up the boot time and general performance you need a faster drive, a solid state drive as your boot drive.

Since that machine is considered obsolete by Apple personally I wouldn't not put any more $$ into it. I'd start saving up for a new or refurbished (only from Apple or OWC-MacSales.com) Mac.

Also that model can only run High Sierra and that's been unsupported by Apple for some time now.

If budgets are an issue you can get a refurbished newer Intel iMac (2019 or newer) from Apple or OWC.

though a mechanical harddrive can only live for so long so spending money on system memory might get followed by spending on a new hd

and then of cause the 2011 imacs had a tendency to end up having their AMD Gpu go belly up that is how mine went years back.

Crucial seems to think so: