What type of RAM does my Apple Mac need?

Apple MacBook, iMac and iPad

Operating systems and applications are getting bigger every year and sooner or later your Apple Mac will become short of memory. You want to upgrade it, but what type should you buy? Finding out is easier than you might think.

Symptoms of memory shortage

When your Mac runs short of memory, one of the first things you will notice is that it operates more slowly than usual. The situation becomes worse with every new app you open. One is OK, two is a bit slow, but the third and fourth seem to take minutes to start up. It is OS X thrashing the disk drive trying to make space in RAM by switching out parts to the disk.

The effect is much more severe with a mechanical disk drive, of course, and it is less of a problem with solid state disks (SSDs) because they work so much faster, but it can still be noticed.

If your Mac seems to be running slowly, open up Activity Monitor in the Applications\Utilities folder. Select the Memory tab at the top and if the memory pressure chart at the bottom is orange or red then you are seriously short of memory.

Adding more memory speeds up the Mac.

There are three problems that must be overcome. You need to know:

  • What type of memory you need to buy
  • How many memory slots are in the Mac
  • The maximum RAM the Mac can accept

Get your Mac’s specifications

There is an easy way to do this and first you go to the Apple menu in the top left corner and select About.

Apple Mac About - get important system information

Select the Memory tab at the top and it shows the number of memory slots in the Mac and the number that are used/free. This Mac has two memory slots and both are used. A 2GB memory module is in each one giving 4GB of memory in total.

Apple Mac system information

See the link in the bottom right corner - Memory Upgrade Instructions - click it.

Safari opens and takes you to a page on the Apple website that lists lots of different models. I am using a MacBook, so I get a list of MacBooks. If you are using an iMac you will probably get a list of iMacs.

Apple Mac models

Which one do your have? There is a link at the top, How to identify MacBook Pro models. Click it. It takes you to a page where you can check your service and support coverage. Go back to the first screenshot (Apple menu, About) and the Mac’s serial number is displayed. Enter it into the box. (Tip, click and drag over the serial number, press Command+C to copy it, click in the box and press Command+V to paste it - it saves typing.)

Apple Mac service

The result of entering the serial number is a page that tells you exactly which MacBook or iMac you have. Here is my result, yours will probably be different.

Apple Mac service and support

Go back to the web page that showed all those Mac models and click the link for your model. The result of that is a web page that displays the number of memory slots, the base memory, maximum memory and memory specifications.

Apple Mac memory specifications

Do not worry if this does not mean anything. You just have to match the specs with the RAM you are buying. In my case I must look for PC3-12800 DDR3 1600 MHz RAM, then make sure it is 204-pin and 67.6mm x 30mm.

The additional notes at the bottom say that it is best to fill both slots with the same memory. I have two slots and need to buy a pair of identical memory modules. The maximum is 8 GB so I need 2 x 4GB modules.

Installing the RAM

Installing the new memory is different for every Mac, so the best advice is to go to the iFixit website and search for your Mac model. I found a superb guide to replacing the memory in my Mac here and many more models are covered.

MacBook Pro 13" Unibody Mid 2012 RAM Replacement



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