Choose your iMac model

• Does It Matter What Slot You Put Your Ram Instrument
• Does It Matter What Slot You Put Your Ram Install
• Does It Matter What Slot You Put Your Ram Instead

As you can see from my post just below this one my computer is fried. My roomate has a Intel computer and I was wondering if i can take the RAM from my AMD system and put it into his computer. If your motherboard lacks an x16 PCIe slot (see above), you should plan on upgrading your motherboard and likely your CPU, RAM and possibly power supply. No matter how hard you shove, this. With equal amounts of memory in both slots, memory can be interleaved so that successive chunks of memory alternate slots. That way, memory access gets distributed to both slots almost perfectly evenly, allowing their bandwidth to combine. With uneven amounts, memory cannot be interleaved and has to be mapped first to one stick and then the other.

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 Authorised Service Provider. If you’d like to upgrade the memory in one of these models, an Apple Authorised Service Provider can help. Before you schedule an appointment, confirm that the specific Apple Authorised 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:

For optimal memory performance, DIMMs should be the same capacity, speed and supplier. 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:

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.

Does It Matter What Slot You Put Your Ram Instrument

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:

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:

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 on the rear of the computer near the vents with these memory specifications:

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've shut down your iMac and given it some time to cool 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. 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 outwards to release the memory cage:
7. After the memory cage has been released, pull the memory cage levers towards 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 orientated 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 you 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 to the left of the centre. If your DIMMs are mixed in capacity, minimise 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 to the left of the centre:
   • 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've installed all of your DIMMs, push both memory cage levers back into the housing until they've locked 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 initialisation 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 you let the memory initialisation 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

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

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've shut down your iMac and given it some time to cool 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 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've inserted 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:

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

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

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 has cooled 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've inserted 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

For best performance, fill both memory slots, installing an equal memory module in each slot.
*iMac (Late 2006) uses a maximum of 3GB 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've shut down your iMac and given it some time to cool 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 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've inserted 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 may 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've shut down your iMac and given it some time to cool 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 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've inserted 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 may 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 recognises its new memory

After you've installed memory, you should confirm that your iMac recognises 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.

If your computer doesn't recognise 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.

If you’re looking to build a gaming computer, your graphics card and processor will play the biggest role in your system’s in-game performance. After those two components, your memory will play the next biggest role in your system’s performance.

In this post, we’ll cover how to choose RAM for your computer. We’ve highlighted four different factors that you should consider when picking memory for your system.

Table of Contents

How Much RAM Do You Really Need?

The quick answer to this question is: most users will likely need 8GB-16GB of RAM.

But, the real answer is: it depends on what kind of system you’re building.

Are you building a high-end workstation PC for video editing/graphics design, etc.? Going with at least 16GB (or more, depending on your budget) would be a wise decision.

Are you building a budget-friendly gaming computer? 8GB is a good start for now.

Yes, there are games that are starting to utilize more than 8GB of RAM, but for the most part, 8GB will still get the job done. Not to mention, RAM is the easiest component in your PC to upgrade. If you have empty DIMM slots on your motherboard, upgrading to more memory is as simple as adding another stick to your system.

So, if you have a larger budget and you’re building a high-end gaming computer or workstation PC, then go with 16GB (or more) to start. If you’ve got a tighter budget, start with 8GB of RAM so that you don’t have to downgrade your CPU and GPU to accommodate more memory.

RAM Compatibility Issues to Be Aware Of

Not all RAM is compatible with every system. Here is a list of things to look for when considering a memory kit’s compatibility with your other components:

• DDR Generation
• Motherboard DIMM Slots
• CPU Heatsink Clearance
• Form Factor

DDR generation is important because older generation DDR memory will not work with motherboards that are built to support newer generation DDR memory and vice versa. You can’t put DDR3 memory in a motherboard that has DDR4 DIMM slots and you can’t put DDR4 memory in a motherboard that has DDR3 DIMM slots.

Speaking of motherboard DIMM slots, it’s also important that you note how many slots your motherboard has. Some smaller form-factor motherboards (micro-ATX and mini-ITX) only come with two DIMM slots. So, obviously, you can’t put a 4x4GB kit of memory in them. You can only have a maximum of two sticks of RAM in that instance. So, make sure you’re not buying more memory sticks than your motherboard can hold.

Certain memory kits can also have compatibility issues with certain CPU heatsinks. Big bulky air CPU coolers can often hang over DIMM slots. And, in some instances, they can prevent memory kits with tall heat spreaders from being installed. So, it’s a good idea to make sure that if you are choosing a big bulky air cooler and you are selecting RAM that has tall heat spreaders, that you check and make sure that your air cooler will not interfere with your RAM.

RAM form-factor is another important thing to consider. There are really only two main RAM form factors:

1. DIMM: desktop form factor
2. SO-DIMM: laptop form factor

All you really need to know here is that if you are building a new desktop PC, or upgrading an existing one, you’ll want to make sure you get DIMM form-factor RAM and not SO-DIMM RAM, as desktop motherboards are not compatible with SO-DIMM memory.

RAM Speed

There’s really just two components that determine the performance of a given memory kit: frequency and latency.

RAM frequency is similar to a CPUs frequency. The faster a memory kit’s frequency is, the faster the memory can process data.

Latency, on the other hand, is the time between when a system command is entered and when it is executed. The lower the latency, the faster the memory can move onto the next process.

Latency and frequency are linked together when determining the overall performance of a given kit of memory, but they are not the same thing.

Does It Matter What Slot You Put Your Ram Install

In general, RAM with higher frequencies will play a bigger role in boosting system performance than will a kit with a lower frequency and a lower latency.

However, it’s also important to note that simply buying the fastest kit of memory on the market will not result in an increase in in-game performance. There is a point of diminishing returns where the faster the memory is, the less of a performance boost it will offer in comparison to a lower frequency.

This can vary, too, depending on how you are using your system and/or what kinds of games you are playing. RAM that operates at higher frequencies can provide performance increases in certain programs and games while having little to no effect on other programs and games.

So, really, in determining what RAM frequency is right for you, you need to evaluate the kinds of programs and games you will be running and determine whether or not faster memory will give you more performance when running them.

Remember, RAM is EASY to Upgrade

Matching your RAM to the quality of your build is also important. You don’t want to put 16GB of RAM in a $500 gaming PC build, as the extra cost of going from 8GB to 16GB is going to mean that you have to downgrade on the components that will have a bigger impact on your in-game performance (like your graphics card and processor).

And, it’s important to remember that RAM is by far the easiest component in your system to upgrade. Because RAM is so easy to upgrade, if you’re working with a tight budget, it makes sense to not go overboard on the amount of memory when choosing components for your system.

To understand the reasoning behind this, consider this scenario…

You’re looking to build an entry-level gaming PC and you decide that you want to put 16GB of RAM in it. The difference between 8GB of RAM and 16GB of RAM is about ~$80. So, essentially, by choosing 8GB of RAM instead of 16GB of RAM, you’re taking $80 from your budget.

Since you’re already working with a tight budget, you probably won’t have room to sacrifice on your motherboard, power supply, and case. And, that really only leaves your CPU and GPU to downgrade in order to accommodate 16GB of RAM. So, you’re sacrificing in-game performance now, so that you can start with 16GB of RAM.

The problem with this is that, if you want to improve your in-game performance, you’ll have to completely replace your CPU and GPU. That means the money spent on your original CPU and GPU is lost (unless you recoup some of the losses by selling them used.)

However, by starting with 8GB of RAM and a better CPU and GPU combo, your first upgrade can be to 16GB of RAM, which will only cost you an additional $80. And, rather than replacing your old memory, all you have to do is add a new stick. So, you don’t lose the money you already put into the system as if you would if you were to upgrade your CPU and GPU.

So, despite a lot of people saying “you need 16GB of RAM for gaming now,” if you don’t have a large budget to spend on your build, starting out with 16GB of RAM is actually going to hurt your performance now, and make your upgrade process in the future more difficult.

Which RAM Will You Choose for Your PC?

For the most part, RAM is a pretty simple component to choose for your system. Your budget will dictate how much RAM you should get. If you have a tight budget, start out with 8GB of RAM, as that should hold you over just fine until you have enough money to add an additional 8GB of RAM.

Does It Matter What Slot You Put Your Ram Instead

If you have a large budget, start with 16GB (or more).

Then, depending on your specific use case, you might want to spend a little more (budget permitting) to get faster RAM with tighter timings.

Ultimately, though, the factors listed above should help you choose the right RAM for your budget and needs.