This process can take 30 seconds or more, and the display of your iMac remains dark until it's finished. Your iMac performs a memory initialization procedure when you first turn it on after upgrading memory or rearranging DIMMs.

Reconnect the power cord and all other cables to the computer, then start up the computer. Place the computer in its upright position.You don't need to press the compartment door release button when replacing the compartment door. After you install all of your DIMMs, push both memory cage levers back into the housing until they lock into place:.iMac (27-inch, Late 2013) and iMac (Retina 5K, 27-inch, Late 2014, Mid 2015, and Late 2015) DIMMs have a notch on the bottom right:.iMac (27-inch, Late 2012) and iMac (Retina 5K, 27-inch, 2017) DIMMs have a notch on the bottom left:.iMac (Retina 5K, 27-inch, 2019) DIMMs have a notch on the bottom, slightly left of the middle:.If your DIMMs are mixed in capacity, minimize the capacity difference between Channel A (slots 1 and 2) and Channel B (slots 3 and 4) when possible. iMac (Retina 5K, 27-inch, 2020) DIMMs have a notch on the bottom, slightly left of the middle.Find your model below for specific installation instructions and notch locations: When you insert a DIMM, make sure to align the notch on the DIMM to the DIMM slot. Replace or install a DIMM by setting it down into the slot and pressing firmly until you feel the DIMM click into the slot.

When reinstalling DIMMs, the notch must be oriented correctly or the DIMM won't fully insert: Remove a DIMM by pulling the module straight up and out. Note the location of the notch on the bottom of the DIMM.After the memory cage is released, pull the memory cage levers toward you, allowing access to each DIMM slot.Push the two levers outward to release the memory cage: Locate the two levers on the right and left sides of the memory cage. A diagram on the underside of the compartment door shows the memory cage levers and the orientation of the DIMM.Remove the compartment door and set it aside: The memory compartment door will open as the button is pushed in.Open the memory compartment door by pressing the small grey button located just above the AC power port:.Hold the sides of the computer and slowly lay the computer face-down on the towel or cloth.Place a soft, clean towel or cloth on the desk or other flat surface to prevent scratching the display.Disconnect the power cord and all other cables from your computer.If you've been using your iMac, wait ten minutes after shutting it down to let the internal components cool.Īfter you shut down your iMac and give it time to cool, follow these steps: The internal components of your iMac can be warm.

Note 20 memory card slot