Install memory in an iMac

Get memory specifications and learn how to install memory in iMac computers.

Choose your iMac model

If you're not sure which iMac you have, you can identify your iMac and then select it from the list below.

*Memory isn't removable by users on iMac (21.5-inch, Late 2012), iMac (21.5-inch, Late 2013), iMac (21.5-inch, Mid 2014), iMac (21.5-inch, 2017), and iMac (Retina 4K, 21.5-inch, 2017). If the memory in one of these computers needs to be replaced, contact an Apple Retail Store or Apple Authorized Service Provider. If you’d like to upgrade the memory in one of these models, an Apple Authorized Service Provider can help.

Memory in iMac (21.5-inch, Late 2015), and iMac (Retina 4K, 21.5-inch, Late 2015) is not upgradeable.

iMac (Retina 5K, 27-inch, 2017)

Get memory specifications for iMac (Retina 5K, 27-inch, 2017), then learn how to install memory in this model.

Memory specifications

This iMac model feature Synchronous Dynamic Random-Access Memory (SDRAM) slots near the bottom of the computer with these memory specifications:

Number of memory slots 4
Base memory 8GB (2 x 4GB DIMMs)
Maximum memory 64GB (4 x 16GB DIMMs)

Use Small Outline Dual Inline Memory Modules (SO-DIMM) that meet all of these criteria:

  • PC4-2400 (19200)
  • Unbuffered
  • Nonparity
  • 260-pin
  • 2400MHz DDR4 SDRAM

iMac (Retina 5K, 27-inch, Late 2015)

Get memory specifications for iMac (Retina 5K, 27-inch, Late 2015), then learn how to install memory in this model.

Memory specifications

This iMac model feature Synchronous Dynamic Random-Access Memory (SDRAM) slots near the bottom of the computer with these memory specifications:

Number of memory slots 4
Base memory 8GB
Maximum memory 32GB

Use Small Outline Dual Inline Memory Modules (SO-DIMM) that meet all of these criteria:

  • PC3-14900
  • Unbuffered
  • Nonparity
  • 204-pin
  • 1867MHz DDR3 SDRAM

For these 27-inch models

Get memory specifications for the following iMac models, then learn how to install memory in them:

  • iMac (Retina 5K, 27-inch, Mid 2015)
  • iMac (Retina 5K, 27-inch, Late 2014)
  • iMac (27-inch, Late 2013)
  • iMac (27-inch, Late 2012)

Memory specifications

These iMac models feature Synchronous Dynamic Random-Access Memory (SDRAM) slots near the bottom of the computer with these memory specifications:

Number of memory slots 4
Base memory 8GB
Maximum memory 32GB

Use Small Outline Dual Inline Memory Modules (SO-DIMM) that meet all of these criteria:

  • PC3-12800
  • Unbuffered
  • Nonparity
  • 204-pin
  • 1600MHz DDR3 SDRAM

Installing memory

The internal components of your iMac can be warm. If you've been using your iMac, wait ten minutes after shutting it down to let the internal components cool.

After you shut down your iMac and give it time to cool, follow these steps:

  1. Disconnect the power cord and all other cables from your computer.
  2. Place a soft, clean towel or cloth on the desk or other flat surface to prevent scratching the display.
  3. Hold the sides of the computer and slowly lay the computer face-down on the towel or cloth.
  4. Open the memory compartment door by pressing the small grey button located just above the AC power port:

     Opening memory compartment door

  5. The memory compartment door will open as the button is pushed in. Remove the compartment door and set it aside:

     Removing compartment door

  6. A diagram on the underside of the compartment door shows the memory cage levers and the orientation of the DIMM. Locate the two levers on the right and left sides of the memory cage. Push the two levers outward to release the memory cage:

     Pushing the two memory cage levers outward to release the memory cage

  7. After the memory cage is released, pull the memory cage levers toward you, allowing access to each DIMM slot.
  8. Remove a DIMM by pulling the module straight up and out. Note the location of the notch on the bottom of the DIMM. When reinstalling DIMMs, the notch must be oriented correctly or the DIMM won't fully insert:

     Removing a DIMM by pulling the module straight up and out

  9. Replace or install a DIMM by setting it down into the slot and pressing firmly until you feel the DIMM click into the slot. The DIMM slot shown below is for iMac (27-inch, Late 2013) and iMac (Retina 5K, 27-inch, Late 2014, Mid 2015, Late 2015, and 2017). It requires that you insert the DIMM with the notch on the bottom, oriented towards the right:
    Inserting the DIMM with the notch on the bottom, oriented towards the right
    iMac (27-inch, Late 2012) has the notch on the bottom left:
    iMac (27-inch, Late 2012) notch on bottom left
  10. After you install all of your DIMMs, push the memory cage levers back into the housing until they click back into place:
     Pushing the memory cage levers back into the housing until they click back into place
  11. Replace the memory compartment door. You don't need to press the compartment door release button when replacing the compartment door.
  12. Place the computer in its upright position. Reconnect the power cord and all other cables to the computer, then start up the computer.

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

For these 27-inch and 21.5-inch models

Get memory specifications for the following iMac models, then learn how to install memory in them:

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

Memory specifications

Number of memory slots 4
Base memory 4GB (but is configured to order)
Maximum memory 16GB
For iMac (Late 2009), you can use 2GB or 4GB RAM SO-DIMMs of 1066MHz DDR3 SDRAM in each slot. For iMac (Mid 2010) and iMac (Mid 2011), use 2GB or 4GB RAM SO-DIMMs of 1333MHz DDR3 SDRAM in each slot.

 Use Small Outline Dual Inline Memory Modules (SO-DIMM) that meet all of these criteria:

iMac (Mid 2011) iMac (Mid 2010) iMac (Late 2009)
PC3-10600 PC3-10600 PC3-8500
Unbuffered Unbuffered Unbuffered
Nonparity Nonparity Nonparity
204-pin 204-pin 204-pin
1333MHz DDR3 SDRAM 1333MHz DDR3 SDRAM 1066MHz DDR3 SDRAM

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.)

Installing memory

The internal components of your iMac can be warm. If you've been using your iMac, wait ten minutes after shutting it down to let the internal components cool.

After you shut down your iMac and give it time to cool, follow these steps:

  1. Disconnect the power cord and all other cables from your computer.
  2. Place a soft, clean towel or cloth on the desk or other flat surface to prevent scratching the display.
  3. Hold the sides of the computer and slowly lay the computer face-down on the towel or cloth.
  4. Using a Philips screwdriver, remove the RAM access door in the bottom of your computer:
     Removing the RAM access door
  5. Remove the access door and set it aside.
  6. Untuck the tab in the memory compartment. If you're replacing a memory module, gently pull the tab to eject any installed memory module:
     Untucking the tab in the memory compartment
  7. Insert your new or replacement SO-DIMM into the empty slot, noting the orientation of the keyway of the SO-DIMM as shown below.
  8. After you insert it, press the DIMM up into the slot. There should be a slight click when you seat the memory correctly:
     Pressing the DIMM up into the slot
  9. Tuck the tabs above the memory DIMMs, and reinstall the memory access door:
     Tucking the tabs above the memory DIMMs
  10. Place the computer in its upright position. Reconnect the power cord and all other cables to the computer, then start up the computer.

For these 24-inch and 20-inch models

Get memory specifications for the following iMac models, then learn how to install memory in them:

  • iMac (24-inch, Early 2009)
  • iMac (20-inch, Early 2009)
  • iMac (24-inch, Early 2008)
  • iMac (20-inch, Early 2008)
  • iMac (24-inch Mid 2007)
  • iMac (20-inch, Mid 2007)

Memory specifications

These iMac computers have two side-by-side Synchronous Dynamic Random-Access Memory (SDRAM) slots in the bottom of the computer.

The maximum amount of random-access memory (RAM) you can install in each computer is:

Computer Memory Type Maximum Memory
iMac (Mid 2007) DDR2 4GB (2x2GB)
iMac (Early 2008) DDR2 4GB (2x2GB)
iMac (Early 2009) DDR3 8GB (2x4GB)

You can use a 1GB or 2GB RAM module in each slot for iMac (Mid 2007) and iMac (Early 2008). Use 1GB, 2GB, or 4GB modules in each slot for the iMac (Early 2009).

Use Small Outline Dual Inline Memory Modules (SO-DIMM) that meet all of these criteria:

iMac (Mid 2007) iMac (Early 2008) iMac (Early 2009)
PC2-5300 PC2-6400 PC3-8500
Unbuffered Unbuffered Unbuffered
Nonparity Nonparity Nonparity
200-pin 200-pin 204-pin
667MHz DDR2 SDRAM 800MHz DDR2 SDRAM 1066MHz DDR3 SDRAM

DIMMs with any of the following features aren't supported:

  • Registers or buffers
  • PLLs
  • Error-correcting code (ECC)
  • Parity
  • Extended data out (EDO) RAM

Installing memory

The internal components of your iMac can be warm. If you've been using your iMac, wait ten minutes after shutting it down to let the internal components cool.

After your iMac cools down, follow these steps:

  1. Disconnect the power cord and all other cables from your computer.
  2. Place a soft, clean towel or cloth on the desk or other flat surface to prevent scratching the display.
  3. Hold the sides of the computer and slowly lay the computer face-down on the towel or cloth.
  4. Using a Philips screwdriver, remove the RAM access door in the bottom of the computer:
     Removing the RAM access door in the bottom of the computer
  5. Remove the access door and set it aside.
  6. Untuck the tab in the memory compartment. If you're replacing a memory module, untuck the tab and pull it to eject any installed memory module:
     Untucking the tab in the memory compartment
  7. Insert your new or replacement RAM SO-DIMM into the empty slot, noting the orientation of the keyway of the SO-DIMM as shown above.
  8. After you insert it, press the DIMM up into the slot. There should be a slight click when you seat the memory correctly.
  9. Tuck the tabs above the memory DIMMs, and reinstall the memory access door:
     Reinstalling the memory access door
  10. Place the computer in its upright position. Reconnect the power cord and all other cables to the computer, then start up the computer.

For these 20-inch and 17-inch models

Get memory specifications for the following iMac models, then learn how to install memory in them:

  • iMac (20-inch Late 2006)
  • iMac (17-inch, Late 2006 CD)
  • iMac (17-inch, Late 2006)
  • iMac (17-inch, Mid 2006)
  • iMac (20-inch, Early 2006)
  • iMac (17-inch, Early 2006)

Memory specifications

Number of memory slots 2
Base memory 1GB Two 512MB DIMMs; one in each of the memory slots iMac (Late 2006)
512MB One DDR2 SDRAM installed into the top slot iMac (17-inch Late 2006 CD)
512MB Two 256MB DIMMs; one in each of the memory slots iMac (Mid 2006)
512MB One DDR2 SDRAM installed into the top slot iMac (Early 2006)
Maximum memory 4GB 2 GB SO-DIMM in each of the two slots* iMac (Late 2006)
2GB 1GB SO-DIMM in each of the two slots iMac (17-inch Late 2006 CD)
iMac (Early 2006)
Memory card specifications Compatible:
- Small Outline Dual Inline Memory Module (DDR SO-DIMM) format
- PC2-5300
- Nonparity
- 200-pin
- 667 MHz
- DDR3 SDRAM
Not compatible:
- Registers or buffers
- PLLs
- ECC
- Parity
- EDO RAM

For best performance, fill both memory slots, installing an equal memory module in each slot.

*iMac (Late 2006) uses a maximum of 3 GB of RAM.

Installing memory in the bottom slot

The internal components of your iMac can be warm. If you've been using your iMac, wait ten minutes after shutting it down to let the internal components cool.

After you shut down your iMac and give it time to cool, follow these steps:

  1. Disconnect the power cord and all other cables from your computer.
  2. Place a soft, clean towel or cloth on the desk or other flat surface to prevent scratching the display.
  3. Hold the sides of the computer and slowly lay the computer face-down on the towel or cloth.
  4. Using a Phillips screwdriver, remove the RAM access door on the bottom of the iMac and set it aside:
     Removing the RAM access door on the bottom of the iMac
  5. Move the DIMM ejector clips to their fully open position:
     Moving the DIMM ejector clips to their fully open position
  6. Insert your RAM SO-DIMM into the bottom slot, keeping in mind the orientation of the keyed SO-DIMM:
     Inserting RAM SO-DIMM into the bottom slot
  7. After you insert it, press the DIMM up into the slot with your thumbs. Don't use the DIMM ejector clips to push in the DIMM, as this might damage the SDRAM DIMM. There should be a slight click when you seat the memory fully.
  8. Close the ejector clips:
     Closing the ejector clips
  9. Reinstall the memory access door:

     Reinstalling the memory access door
  10. Place the computer in its upright position. Reconnect the power cord and all other cables to the computer, then start up the computer.

Replacing memory in the top slot

After you shut down your iMac and give it time to cool, follow these steps:

  1. Disconnect the power cord and all other cables from your computer.
  2. Place a soft, clean towel or cloth on the desk or other flat surface to prevent scratching the display.
  3. Hold the sides of the computer and slowly lay the computer face-down on the towel or cloth.
  4. Using a Phillips screwdriver, remove the RAM access door on the bottom of the iMac and set it aside:
     Removing the RAM access door on the bottom of the iMac
  5. Pull the two levers on each side of the memory compartment to eject the memory module that's already installed:
     Ejecting the memory module that's already installed
  6. Remove the memory module from your iMac as shown below:
     Removing the memory module
  7. Insert your RAM SO-DIMM into the top slot, noting the orientation of the keyed SO-DIMM:
     Inserting RAM SO-DIMM into the top slot
  8. After you insert it, press the DIMM up into the slot with your thumbs. Don't use the DIMM ejector clips to push in the DIMM, as this might damage the SDRAM DIMM. There should be a slight click when you seat the memory fully.
  9. Close the ejector clips:
     Closing the ejector clips
  10. Reinstall the memory access door:
     Reinstalling the memory access door
  11. Place the computer in its upright position. Reconnect the power cord and all other cables to the computer, then start up the computer.

If your iMac makes a tone after you install memory

iMac models introduced before 2017 might make a warning sound when you start up after installing or replacing memory:

  • One tone, repeating every five seconds signals that no RAM is installed.
  • Three successive tones, then a five-second pause (repeating) signals that RAM doesn't pass a data integrity check.

If you hear these tones, confirm that the memory you installed is compatible with your iMac and that it's installed correctly by reseating the memory. If your Mac continues to make the tone, contact Apple Support.

Confirm that your iMac recognizes its new memory

After you install memory, you should confirm that your iMac recognizes the new RAM by choosing Apple () menu > About This Mac.

The window that appears lists the total memory, including the amount of memory that originally came with the computer plus the newly added memory. If all the memory in the iMac has been replaced, it lists the new total of all installed RAM.

About This Mac

For detailed information about the memory installed in your iMac, click System Report. Then choose Memory under the Hardware section in the left side of System Information.

System Information

If your computer doesn't recognize the memory or doesn't start up correctly, confirm that the RAM you installed is compatible with your iMac and that it's installed correctly by reseating the memory. If you continue to have issues with the memory in your iMac, contact Apple Support.

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