Mac can be conveniently purchased from the Apple store and most of configuration allows you to upgrade the memory so that you don’t need to open the case and take the risk in using an incompatible memory which would cause system lockups.

The only thing is the upgrade from Apple store cost a lot more money if compared to the one that it purchased from a computer store. For example, an additional 2GB of memory cost $50 at Apple Store while it only cost less than $10 if you search in Pricewatch. If you’re willing to take the risk in adding extra memory in your Mac either to save money or perhaps you have a few lying around, it is best to run a memory test to make sure that the RAM is fully compatible and won’t make your Mac unstable.

Shop for mac memory at Best Buy. Find low everyday prices and buy online for delivery or in-store pick-up. Best Buy customers often prefer the following products when searching for Mac Memory. Browse the top-ranked list of Mac Memory below along with associated reviews and opinions. Apple has guidelines for the maximum amount of RAM each iMac model supports, but upgrade specialists say the devices are capable of supporting more. While earlier versions of the iMac (17-inch or 20-inch models from 2006) have two memory slots, starting with 2007 models Apple decided to implement four slots instead. Best computer specs for gaming. Best gaming SSD. Upgrading Computer. How Crucial DRAM and SSDs add speed for creatives. DDR4 RAM memory. DDR3 RAM memory. DDR2 RAM memory. Computer storage. All Crucial SSDs. Upgrade your 2018 Mac mini or your 2019 27-inch iMac with the best memory up to 0.8GB with Mac Sales & OWC promotion.

Here we suggest 3 different methods to easily run a memory test on your Mac OS X including the latest Mountain Lion 10.8.

1. Rember

Rember is actually a GUI for the popular command line memory testing tool called Memtest OS X. Instead of typing commands in terminal, you can run the test by clicking a button. You are able to test a selected amount or all of the memory, specify the number of times the tests should run and also viewing of the log. Rember includes Memtest OS X in the package so there is no need to manually download and install the memtest. Running Rember will show a table displaying the detected memory on your Mac. Select the amount of memory to test, number of loops and click the Test button to start checking the memory. When the tests is finished, Rember will show the test results.

Rember runs in Mac OS X which means that not all of the ram can be tested due to a portion of RAM being reserved for housekeeping.

Download Rember

2. Memtest86+

If your Mac has a SuperDrive, you can burn the pre-compiled bootable ISO image of the Memtest86+ and boot up the Mac with the disc. Just press and hold the C key when starting up Mac to boot from the disc.

The good thing about Memtest86+ is it runs by itself without relying on the operating system, giving you a more accurate memory test result.

Download Memtest86+

3. Apple Hardware Test

This is the recommended way by Apple to test your memory using their diagnostic tool. If you have an installation disc, insert the disc, restart your Mac, press and hold the C key. Select the language for the Apple Hardware Test and click the Test button to start testing. You can also tick the “Perform extended testing” option which would perform a more thorough test that takes considerably more time to complete. On the latest Mac OS X Mountain Lion, the Apple Hardware Test is already pre-installed and it doesn’t come with an installation disc. Simply boot up, press and hold the D key to start the Apple Hardware Test.

You can also see the amount of memory installed on your Mac at the Hardware Profile tab to confirm that the memory is correctly installed and detected. There are some Apple Hardware Test images that can be downloaded for older models. Do note that the Apple Hardware Test images are machine specific meaning that you cannot use the iBook version on a Mac Mini.

Download Apple Hardware Test

You might also like:

3 Ways to Test your RAM with Microsoft Windows Memory Diagnostic6 Free Programs to Check Your Video Card Memory For Errors10 Popular Web Browsers Tested for Memory and CPU UsageDownload Sony Memory Card File Rescue Software for Free.NET Framework Setup Verification Utility

‘Closing all apps’ is an option which can be set or disabled in the Rember preferences.

Reply

I’m trying to test DRAM one bank at a time in mid-2010 Mac mini with 2 banks of 4GB Kingston DRAM each.

Rember run overnight on max cycles (255) showed when both banks were full (8GB total), there was a DRAM failure. But run overnight on max cycles (255), Rember is so slow it’s completed less than 30 cycles. I tried this twice.

Is it not possible to check one 4GB stick at a time? (Mid-2010 Mac mini standard RAM is 1GB module in each bank for total 2GB.)

Reply

I have several DDR3 DIMMs I want to install, but the memory timing is not printed on them. Is there an app for Macs that can tell you what the timing is on installed DIMMs?

Reply

Rember doesn’t shut down existing programs… you do that yerself

Reply

Rember is an amazing app! In regards to the comment above:

it closes all windows because to free-up whole RAM memory for tests.
It’s understandable that you must save your work before you open any diagnostic app.

Works great on latest 2019 iMac where Memtest failed and Apple Diagnostic Tool is a JOKE

Reply

Rember

I ran this app and it closed all open windows and running apps without asking or warning me. That is bad software. Who knows what data I lost as a result, let alone time in reopening what I can remember was running. memtest does not do this.

Reply

Hope this works well, thanks!

Reply

Choose your iMac model

Best Memory For Macbook

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

27-inch

24-inch

21.5-inch

• iMac (Retina 4K, 21.5-inch, 2019)*
• iMac (Retina 4K, 21.5-inch, 2017)*
• iMac (21.5-inch, 2017)*
• iMac (21.5 inch, Mid 2014)*
• iMac (21.5-inch, Late 2013)*
• iMac (21.5-inch, Late 2012)*

20-inch

17-inch

* Memory is not 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), iMac (Retina 4K, 21.5-inch, 2017), and iMac (Retina 4K, 21.5-inch, 2019). If the memory in one of these computers needs repair service, 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. Before you schedule an appointment, confirm that the specific Apple Authorized Service Provider offers memory upgrade services.

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, 2020)

Get memory specifications for iMac (Retina 5K, 27-inch, 2020), then learn how to install memory in this model.

Memory specifications

This iMac model features Synchronous Dynamic Random-Access Memory (SDRAM) slots on the rear of the computer near the vents with these memory specifications:

Number of memory slots	4
Base memory	8GB (2 x 4GB DIMMs)
Maximum memory	128GB (4 x 32GB DIMMs)

For optimal memory performance, DIMMs should be the same capacity, speed, and vendor. Use Small Outline Dual Inline Memory Modules (SO-DIMM) that meet all of these criteria:

• PC4-21333
• Unbuffered
• Nonparity
• 260-pin
• 2666MHz DDR4 SDRAM

If you have mixed capacity DIMMs, see the install memory section for installation recommendations.

iMac (Retina 5K, 27-inch, 2019)

Get memory specifications for iMac (Retina 5K, 27-inch, 2019), then learn how to install memory in this model.

Memory specifications

This iMac model features Synchronous Dynamic Random-Access Memory (SDRAM) slots on the rear of the computer near the vents 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:

• PC4-21333
• Unbuffered
• Nonparity
• 260-pin
• 2666MHz DDR4 SDRAM

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 features Synchronous Dynamic Random-Access Memory (SDRAM) slots on the rear of the computer near the vents 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 features Synchronous Dynamic Random-Access Memory (SDRAM) slots on the rear of the computer near the vents 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)

Best Memory For Macbook Air

Memory specifications

These iMac models feature Synchronous Dynamic Random-Access Memory (SDRAM) slots on the rear of the computer near the vents 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:
5. The memory compartment door will open as the button is pushed in. Remove the compartment door and set it aside:
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:
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:
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. When you insert a DIMM, make sure to align the notch on the DIMM to the DIMM slot. Find your model below for specific installation instructions and notch locations:
   • iMac (Retina 5K, 27-inch, 2020) 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, 2019) DIMMs have a notch on the bottom, slightly left of the middle:
   • iMac (27-inch, Late 2012) and iMac (Retina 5K, 27-inch, 2017) DIMMs have a notch on the bottom left:
     
   • 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:
     
10. After you install all of your DIMMs, push both memory cage levers back into the housing until they lock 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:
   
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:
   
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:
   
9. Tuck the tabs above the memory DIMMs, and reinstall 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 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:
   
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:
   
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:
   
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:
   
5. Move 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:
   
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:
   
9. Reinstall 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:

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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:
   
5. Pull the two levers on each side of the memory compartment to eject the memory module that's already installed:
   
6. Remove the memory module from your iMac as shown below:
   
7. Insert your RAM SO-DIMM into the top slot, noting the orientation of the keyed SO-DIMM:
   
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:
   
10. Reinstall 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.

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.

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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.