iMac (Late 2009) and later: Installing or replacing memory

Summary

Learn how to install additional memory or replace the memory in your iMac (Mid 2011), iMac (Mid 2010), or iMac (Late 2009) computer.

Products Affected

iMac (21.5-inch, Late 2009), iMac (21.5-inch, Mid 2010), iMac (21.5-inch, Mid 2011), iMac (27-inch, Late 2009), iMac (27-inch, Mid 2010), iMac (27-inch, Mid 2011)

The iMac (21.5-inch, Mid 2011), iMac (27-inch, Mid 2011), iMac (21.5-inch, Mid 2010), iMac (27-inch, Mid 2010), iMac (21.5-inch, Late 2009), and iMac (27-inch, Late 2009) computers have four SO-DIMM DDR3 SDRAM (Synchronous Dynamic Random-Access Memory) slots located in the bottom of the computer.

The maximum amount of SDRAM you install in the computer is 16 GB; a 4 GB SO-DIMM (Small Outline Dual Inline Memory Module) in each slot. For the iMac (Late 2009) models, you can use 2 GB or 4 GB RAM SO-DIMMs of 1066 MHz DDR3 SDRAM in each slot. For the iMac (Mid 2011) and iMac (Mid 2010) models, use 2 GB or 4 GB RAM SO-DIMMs of 1333 MHz DDR3 SDRAM in each slot.

Notes:

i5 and i7 Quad Core iMac computers come with both top memory slots populated. These computers will not start up if only a single DIMM is installed in any bottom slot; these computers should operate normally with a single DIMM installed in any top slot. Core Duo iMac computers should operate normally with a single DIMM installed in any slot, top or bottom. ("Top" and "bottom" slots refer to the orientation of the slots in the pictures below. "Top" refers to the slots closest to the display; "bottom" refers to the slots closest to the stand).

Use SO-DIMMs that meet certain criteria.

To install memory into the bottom slot, follow these instructions:

Turn off your computer by choosing Shut Down from the Apple () menu.
Disconnect all cables and the power cord from your computer.
Place a soft, clean towel or cloth on the desk or other flat surface to prevent scratching the LCD display.
Hold the sides of the computer and slowly lay the computer face-down.
Using a Philips screwdriver, remove the RAM access door in the bottom of your computer.
Remove the access door and set it aside.
Untuck the tab in the memory compartment. If you are replacing a memory module, gently pull the tab to eject any installed memory module.
Insert your new or replacement SO-DIMM into the empty slot, keeping in mind the orientation of the keyway of the SO-DIMM as shown below.
Once inserted, press the DIMM up into the slot. There should be a slight click when the memory is seated correctly.
Tuck the tabs above the memory DIMMs, and re-install the memory access door.
Stand the computer in its upright position, reconnect the power cord and all other cables to the computer, then start up the computer.