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Installing RAM – Macintosh

iMac 21.5 inch Retina
iMac 27 inch Retina
iMac 17-27 inch 2006-2011 models
Testing RAM

All Mac install Videos
Apple memory installation guides

iMac 21.5 inch Retina 2012 – 2020

These machines do not have user replaceable RAM. 2 RAM sockets can be accessed by de-laminating the display from the body of the machine, and removing the motherboard. This is a job for a professional technician. Email us for more information.

iMac 27 inch Retina 2012 – 2020

There is a hatch on the back of the machine, with a drawer that hinges down to reveal four RAM sockets. First lay the machine face down on a stable surface, preferably on a towel. You release the hatch door by pressing a button on the back, that is revealed near the power input when you have removed the power cable.

iMAc 27 memory install


iMac 2006 to Mid 2011 non-Retina, 20, 21.5, 24 and 27 inch

Machines with blind push-in slots.
Note: A good 50% of RAM ‘failures’ in these machines are actually due to incomplete seating of the RAM module in the socket.

These machines are tricky because you cannot see what you are doing, the module is a straight push into the slot.

  • There is usually a metal cover plate to unscrew to expose the slots. The screws on most models are captured, they do not remove all the way.

  • You may have to remove the existing module(s). There will be levers or some vinyl tape to pull on to loosen the module, it will not spring them all the way out so don’t pull violently on the mechanism.  Use your fingers to pull the RAM module out (do NOT use pliers or other tools, they will damage the module).

  • As the older module comes out, observe the orientation of the slot on the connector edge, you will want to insert the new RAM module the same way.  If you didn’t see which side the slot is on, look inside the socket with a flashlight, or look for a legend printed on the machine, or refer to your owners manual or Apple’s web site. Do not force a module in if you are uncertain of the orientation.SODIMM Slot Load picture

  • Insert the new RAM module in the socket in the correct orientation , and push it in.  It will go in about 1 inch (2.5cm) and then stop. You are not done yet…

  • Get both thumbs on the long edge of the module and push quite firmly. The module will go in another 1/8th inch (2mm) to seat fully into the socket. (Contrary to Apple’s instructions, there is no audible click as it is seated, more of a soft thunk you can feel more than hear). Check that it is fully seated on both ends of the module. If you don’t have dents on the ends of your thumbs, then you haven’t pushed hard enough.

  • If the machine has 2 plastic lever clips at the ends of the module, you can gently move these back into the closed position – but do not use these to push in the RAM module, it will damage the clips and/or the module.  If the clips do not go back without pushing, that means that the module is not fully inserted.
    If the machine has a single horizontal lever, this has no role in inserting the module.

  • After you have tested the RAM, reinstall the coverplate over the RAM sockets. If the plate does not go back into place flush, that means that the module is not fully inserted.

Testing RAM

You can test newly installed Macintosh RAM with a free utility called Rember

Install videos for all Macs

Find installation video guides for your Mac model at OWC’s video gallery

Apple memory installation instructions for


MacBook Pro –  MacBook

iMac Intel –  iMac G5 iSight model  –  iMac G5 pre-iSight

MacMini Intel

PowerBook G4 17″ Al  –  PowerBook G4 15″ Al –  Powerbook G4 12″ Al –  PowerBook G4 Titanium

Memory configurations for earlier PowerMacs

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