My iMac is running slow and I am hoping to get a few more years out of it. I figure I have two options:

  1. add memory
  2. replace my current hard drive with one that is solid state.

So I am tackling the memory option first. My iMac has four memory slots with two in use. The two in use each have an 8GB module. What can I add in the empty slots? 4GB or 8GB modules? Also, can someone provide a link to a company so this newbie can purchase the correct modules? For example:



3 Answers 3


I'd suggest you look at your RAM usage in Activity Monitor first. 16 Gb is plenty for most tasks. If you're seeing low memory pressure (Green on the graph), then you might be better off with the SSD first.

Here's an example of very low RAM usage: tiny amount of Green; no Swap, no Compressed memory. If you've been running for a long time, you can expect some swap.

Memory Pressure

Here's a similar setup using 8Gb of RAM, which is coping, but could benefit from more RAM:

Memory Pressure 2

Pressure is still green, but higher. It's not Yellow or Red, though; but it's having to compress some memory to cope.

Don't forget that MacOS tries to use as much memory as possible, so simply using lots of RAM is not an indicator that you need more.

An SSD will be a much more noticeable improvement, with app launches, document loading and other disk-related activities all being orders of magnitude faster.

  • I currently have a 3 TB SATA disk and am using 1.97 TB. Do they make an affordable 3 TB SSD that is affordable? if so, can I install it myself? Commented Feb 19, 2020 at 19:50
  • Yes, you can even get a 4TB SATA SSD. Not cheap, though. You might do well to get a 1Gb unit for the OS, Applications and some of your data, farming out stuff that doesn't need the speed to an external HDD. For instance, Audio files don't benefit from the extra speed.
    – benwiggy
    Commented Feb 19, 2020 at 19:53
  • I watched my memory pressure and it was about 1/3 high. Physical Memory: 16.00 GB Memory Used: 10.33 GB Cached Files: 4.42 GB Swap Used: 440.8 MB So adding memory may be a disappointment. I now realize I should have asked my question differently. As one might expect, my computer has slowed as OS upgrades are made. However, recently my computer seems to "go out to lunch". I am working on something and then no applications respond. They could be for 10-45 seconds. How do I find the culprit? Maybe that will direct me to the appropriate fix. Commented Feb 19, 2020 at 20:15
  • Perhaps ask a new question. But I'd suspect a 7-year-old hard drive as reaching end-of-life.
    – benwiggy
    Commented Feb 19, 2020 at 21:07

You can check memory requirements & max RAM using Everymac & search for your exact model.

Assuming I got it right, this is yours - https://everymac.com/systems/apple/imac/specs/imac-core-i5-3.2-27-inch-aluminum-late-2013-specs.html
RAM is 1600 MHz PC3-12800 DDR3 SDRAM SO-DIMMs (204-pin) max 32GB.

They also list sponsors & direct links to stores around the world who sell matching memory. Everymac will presumably get some reciprocation for these links, but as the information repository they have is available for free, I personally would not begrudge them this.

Alternatively, search for "online memory configurator" for other resources.

From personal experience, you won't see the full benefit of the additional RAM until you put a nice big SSD in there too.

  • I currently have a 3 TB SATA disk and am using 1.97 TB. Do they make an affordable 3 TB SSD that is affordable? if so, can I install it myself? Commented Feb 19, 2020 at 19:48

You can put 8 GB ram in each of the remaining slots to give you 32 GB. I suggest Other World Computing, OWC. Crucial used to be the most reliable or so I read somewhere so Amazon should be fine as well.

The OWC site has a DIY video to instruct you on installing the memory.

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