Introduction

Use this guide to replace or upgrade the CPU. Don't forget to apply a new layer of thermal compound before reassembling your iMac.

What you need

Step 1 Display

iMac Intel 21.5" EMC 2544 CPU Replacement, Display: step 1, image 1 of 1

Tool used on this step:

iMac Intel 21.5" Cardboard Service Wedge

$4.99

Buy

With the hinge free to move, the iMac will be unbalanced and hard to work on. Repairs can be completed as shown, but are faster and easier with an iMac service wedge.
If you are using the iFixit cardboard service wedge, follow these assembly directions to put it together.
Before beginning any work on your iMac: Unplug the computer and press and hold the power button for ten seconds to discharge the power supply's capacitors.
Be very careful not to touch the capacitor leads or any exposed solder joints on the back of the power supply. Only handle the board by the edges.

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Step 2

Starting on the left of the display, near the power button, insert the iMac Opening Tool into the gap between the glass panel and the rear enclosure.
The hub on the iMac Opening Tool will keep you from pushing the wheel in too far. If using a different tool, insert no more than 3/8" into the display. Otherwise, you risk severing antenna cables and causing serious damage.
Be gentle! The glass may crack if pried too much. Use a hairdryer to heat the edges and loosen the tape if the room temperatures are low.

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Step 3

iMac Intel 21.5" EMC 2544 CPU Replacement: step 3, image 3 of 3

Use the tool like a pizza cutter—roll it along through the gap, and it will cut the foam adhesive through the center.
Be sure to always push with the handle behind the cutting wheel. If you pull, the wheel might get pulled out of the handle.
Run the tool up along the left side of the display.

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Step 4

iMac Intel 21.5" EMC 2544 CPU Replacement: step 4, image 3 of 3

Continue running the tool up around the top left corner.

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Step 5

Cut the adhesive along the top left of the display.

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Step 6

Continue along the top of the display.
You may want to run the tool back and forth through what you've already cut a few times, to ensure you get as much of the adhesive separated as possible.

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Step 7

iMac Intel 21.5" EMC 2544 CPU Replacement: step 7, image 3 of 3

Push the tool around the top right corner of the display.

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Step 8

Wheel the tool down along the right side of the display.

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Step 9

Finish pushing the opening tool to the bottom of the right side of the display.
At this point, you'll want to run the tool back around the entire display, to ensure you cut as much adhesive as possible.

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Step 10

iMac Intel 21.5" EMC 2544 CPU Replacement: step 10, image 3 of 3

Tool used on this step:

Plastic Cards

$2.99

Buy

While the opening tool cut most of the adhesive, the display will still be slightly adhered to the case. A plastic card will be necessary to free up the last of this adhesive.
Set the iMac face-up on a table.
Starting from the top right corner of the iMac, wedge a plastic card between the display and frame.
Be careful not to insert the plastic card more than 3/8", or you may damage internal components.

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Step 11

Gently twist the plastic card sideways to create a gap between the display and frame.
Move slowly and be careful not to stress the display glass too much—you only need to make a gap of about 1/4".

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Step 12

iMac Intel 21.5" EMC 2544 CPU Replacement: step 12, image 3 of 3

Slide the card toward the center of the display to cut any of the remaining adhesive along the top right corner of the iMac.
Be sure to stop before the iSight camera, or you may damage it.

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Step 13

Wedge the plastic card into the top right corner once again and let it stay there to keep the adhesive from resettling.

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Step 14

iMac Intel 21.5" EMC 2544 CPU Replacement: step 14, image 3 of 3

Insert a second plastic card into the gap between the display and frame located at the top left corner of the iMac.

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Step 15

Gently twist the card upward, slightly increasing the space between the display and frame.
As with the other side, twist slowly to allow the adhesive time to separate, and be careful not to over-stress the display glass.

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Step 16

iMac Intel 21.5" EMC 2544 CPU Replacement: step 16, image 3 of 3

Slide the plastic card toward the center, again stopping just before the iSight camera.

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Step 17

Wedge the plastic card back into the top left corner.

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Step 18

iMac Intel 21.5" EMC 2544 CPU Replacement: step 18, image 3 of 3

With both plastic cards inserted as shown near the corners, gently twist the cards sideways to increase the gap between display and case.
If there are any sections that seem to stick and won't separate, stop twisting and use one of the cards to cut the remaining adhesive.
Begin to lift the top of the display up from the frame.
Only lift the display a few inches—the display data and power cables are still connected to the logic board.

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Step 19

While holding the display up with one hand, use the other hand to unplug the display power cable. Make sure that you pull the cable out from the plastic tab, and not by pulling on the color wires.
Lift the display up enough to have easy access to the connector, but not so much that you stretch the cables and stress their connections (about 8").

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Step 20

iMac Intel 21.5" EMC 2544 CPU Replacement: step 20, image 3 of 3

Use the tip of a spudger to flip up the metal retaining bracket on the display data cable.
Carefully pull the display data cable from its socket on the logic board.
Be sure to pull the display data cable connector straight out of its socket.

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Step 21

Lift the display up to a near-vertical position.
At this point there is still a strip of adhesive along the bottom of the display, that will hold the display to the frame like a hinge. You can loosen this adhesive by working the display up and down a few times.

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Step 22

iMac Intel 21.5" EMC 2544 CPU Replacement: step 22, image 3 of 3

Be very careful not to touch the capacitor leads or any exposed solder joints on the back of the power supply (boxed in red).
Grasp the small tab at the end of one of the bottom edge display adhesive strips and pull the adhesive toward the top of the iMac to remove it.
Repeat this step with the other adhesive strip and remove it.
If either adhesive strip breaks before it's removed, use a plastic card to slice through the remaining adhesive.

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Step 23

iMac Intel 21.5" EMC 2544 CPU Replacement: step 23, image 3 of 3

Lift the display up from the frame and remove it from the iMac.
It may be necessary to slowly lift from one side, to peel against the remaining adhesive.
Be very careful handling the display—it's big, heavy, and made of glass.
During reassembly, head over to our display adhesive guide to install the new adhesive.

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Step 24 Lower Support Bracket

iMac Intel 21.5" EMC 2544 CPU Replacement, Lower Support Bracket: step 24, image 1 of 2

iMac Intel 21.5" EMC 2544 CPU Replacement, Lower Support Bracket: step 24, image 2 of 2

Remove the following five Phillips screws holding the lower support bracket in place:
Four 3.2 mm screws
One 1.7 mm screw
On at least some EMC 2544 machines, all five screws are the same size.
You may need to peel up the display adhesive lining the bottom edge of the iMac enclosure to access the screws.

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Step 25

Remove the lower support bracket from the iMac enclosure.

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Step 26 Right Speaker

iMac Intel 21.5" EMC 2544 CPU Replacement, Right Speaker: step 26, image 1 of 2

iMac Intel 21.5" EMC 2544 CPU Replacement, Right Speaker: step 26, image 2 of 2

Use a spudger to loosen the right speaker cable's connector from its socket on the logic board.
It is useful to push downward on both short sides of the connector to "walk" it out of its socket. Be careful with the corners of the connectors, they can be easily broken off.
Pull the connector downwards to remove it from its socket.

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Step 27

Remove the two 10.0 mm T10 screws securing the right speaker to the rear enclosure.

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Step 28

Pull the top of the right speaker away from the rear enclosure, about half an inch, to expose the antenna cable running down its right side.

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Step 29

iMac Intel 21.5" EMC 2544 CPU Replacement: step 29, image 3 of 3

Insert the tip of a spudger between the right speaker and the antenna cable that is routed into the speaker's right side.
Run the spudger down along the right side of the speaker to pry the antenna cable from its channel in the right speaker.

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Step 30

iMac Intel 21.5" EMC 2544 CPU Replacement: step 30, image 3 of 3

Pull the right speaker straight up about an inch, toward the top of the iMac.
Lift the right speaker straight up and remove it from the iMac. This may take some force, both hands and rocking the speaker right and left to get it out.

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Step 31 Hard Drive Brackets

iMac Intel 21.5" EMC 2544 CPU Replacement, Hard Drive Brackets: step 31, image 1 of 1

Remove the following screws securing the hard drive bracket to the rear enclosure:
Two 21 mm T10 Torx screws from the left-hand hard drive bracket.
One 9 mm T10 Torx screw.
One 27 mm T10 Torx screw.

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Step 32

Remove the left and right hard drive brackets from the iMac.

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Step 33 Power Supply

iMac Intel 21.5" EMC 2544 CPU Replacement, Power Supply: step 33, image 1 of 3

iMac Intel 21.5" EMC 2544 CPU Replacement, Power Supply: step 33, image 2 of 3

iMac Intel 21.5" EMC 2544 CPU Replacement, Power Supply: step 33, image 3 of 3

The next few steps bring your hands close to the exposed face of the power supply. Do not touch the face of the power supply to avoid a high voltage shock from the many large capacitors attached to the board.
Use the tip of a spudger to push each side of the power button cable connector and gently "walk" it out of its socket.

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Step 34

Gently push upward on each side of the power supply control cable connector with the tip of a spudger to gently "walk" it out of its socket.

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Step 35

Remove the two 7.2 mm T10 screws securing the power supply to the rear enclosure.

Edit

Step 36

When working on the power supply, be very careful not to touch the capacitor leads or any exposed solder joints on the back of the power supply. Only handle the board by the edges.
Tilt the power supply forward.

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Step 37

iMac Intel 21.5" EMC 2544 CPU Replacement: step 37, image 3 of 3

Pull the power supply slightly up and out from the rear enclosure.
Rotate the power supply counterclockwise, lifting the right side up about an inch higher than the left.

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Step 38

Slide the power supply to the right to clear the screw posts on the rear enclosure.

Edit

Step 39

iMac Intel 21.5" EMC 2544 CPU Replacement: step 39, image 3 of 3

Rock the power supply forward and remove it from its recess in the rear enclosure.
Do not try to completely remove the power supply from the iMac yet—it is still connected to the logic board.

Edit

Step 40

Be very careful not to touch the capacitor leads or any exposed solder joints on the back of the power supply. Only handle the board by the edges.
Flip the top of the power supply towards you to access the DC power cable connection behind the logic board.
Squeeze the DC power cable connector tab and pull it straight out of its socket on the back of the logic board.

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Step 41

iMac Intel 21.5" EMC 2544 CPU Replacement: step 41, image 3 of 3

You may find it helpful to set the iMac down on its back on the table for the next couple of steps.
Use the flat end of a spudger to push the clip on the side of the AC inlet cable connector inward.
While holding on the release clip with the spudger, grasp the AC inlet cable, and pull the connector straight out of its socket.

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Step 42

Remove the power supply from the iMac.

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Step 43 Fan

iMac Intel 21.5" EMC 2544 CPU Replacement, Fan: step 43, image 1 of 2

iMac Intel 21.5" EMC 2544 CPU Replacement, Fan: step 43, image 2 of 2

Gently pull the fan cable connector straight away from its socket on the logic board.

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Step 44

Remove the three 12.3 mm T10 shoulder screws securing the fan to the rear enclosure.

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Step 46 Hard Drive

iMac Intel 21.5" EMC 2544 CPU Replacement, Hard Drive: step 46, image 1 of 3

iMac Intel 21.5" EMC 2544 CPU Replacement, Hard Drive: step 46, image 2 of 3

iMac Intel 21.5" EMC 2544 CPU Replacement, Hard Drive: step 46, image 3 of 3

Lift the hard drive from the edge nearest the logic board and pull it slightly out of its recess.
The hard drive is attached by two cables, do not attempt to fully remove it from the iMac.

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Step 48

Unplug the SATA data cable from the hard drive.

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Step 49

Remove the hard drive from the iMac.

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Step 50 Hard Drive Tray

iMac Intel 21.5" EMC 2544 CPU Replacement, Hard Drive Tray: step 50, image 1 of 1

Remove the single 7.2 mm T10 screw securing the hard drive tray to the rear enclosure.

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Step 51

Remove the hard drive tray from the rear enclosure.

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Step 52 Logic Board Assembly

iMac Intel 21.5" EMC 2544 CPU Replacement, Logic Board Assembly: step 52, image 1 of 2

iMac Intel 21.5" EMC 2544 CPU Replacement, Logic Board Assembly: step 52, image 2 of 2

Push on each side of the left speaker cable connector with the tip of a spudger and gently "walk" it out of its socket.

Edit

Step 53

De-route the left speaker cable by pulling it straight up out of the retaining clip in the back of the rear enclosure.

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Step 54

iMac Intel 21.5" EMC 2544 CPU Replacement: step 54, image 3 of 3

In a similar fashion as the previous step, de-route the SATA data and power cables up out of the retaining clip.

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Step 55

iMac Intel 21.5" EMC 2544 CPU Replacement: step 55, image 3 of 3

Use the flat edge of a spudger to flip up the metal retaining bracket on the iSight camera cable connector.
Pull the iSight camera cable straight out of its socket on the logic board.
This is a delicate connector that can be easily damaged.

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Step 56

iMac Intel 21.5" EMC 2544 CPU Replacement: step 56, image 3 of 3

Use the flat edge of a spudger to disconnect each of the four antenna connectors from the AirPort/Bluetooth card.
Note the original positions for each connector when reconnecting the cables.

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Step 57

If brackets secure the four antenna cables, remove the two T5 Torx screws from the brackets.

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Step 58

iMac Intel 21.5" EMC 2544 CPU Replacement: step 58, image 3 of 3

Use the flat edge of a spudger to pry the headphone jack cable connector from its socket on the logic board.
Push the cable slightly to the right.

Edit

Step 59

Remove the following screws securing the exhaust duct to the rear enclosure:
Two 6.3 mm T8 screws
Two 4.7 mm T8 screws

Edit

Step 60

Remove the four 7.2 mm T10 screws securing the logic board to the rear enclosure.
Depending on the age and model of your iMac, a T9 driver may work best.

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Step 61

iMac Intel 21.5" EMC 2544 CPU Replacement: step 61, image 3 of 3

Tilt the top of the logic board away from the rear enclosure.
Lift the logic board straight up and out of the iMac.
Be careful not to snag the board on any of the rear case's screw posts.
The I/O boards at the bottom of the logic board will be the greatest challenge. It is recommended to pull gently to avoid any damage.
During reassembly of the logic board, pay attention to the position of the I/O connectors. When the board is back in the case, insert a USB or Thunderbolt cable into one of the connectors to align it perfectly.

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Step 62 RAM

iMac Intel 21.5" EMC 2544 CPU Replacement, RAM: step 62, image 1 of 3

iMac Intel 21.5" EMC 2544 CPU Replacement, RAM: step 62, image 2 of 3

iMac Intel 21.5" EMC 2544 CPU Replacement, RAM: step 62, image 3 of 3

Release the tabs on each side of the RAM module by simultaneously pushing each tab away.
The RAM module should pop up slightly from its socket.
Grab the top left and right corners of the RAM module and carefully pull it straight out of its socket.
Repeat the process to remove additional RAM modules as necessary.

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Step 63 Heat Sink Assembly

iMac Intel 21.5" EMC 2544 CPU Replacement, Heat Sink Assembly: step 63, image 1 of 3

iMac Intel 21.5" EMC 2544 CPU Replacement, Heat Sink Assembly: step 63, image 2 of 3

iMac Intel 21.5" EMC 2544 CPU Replacement, Heat Sink Assembly: step 63, image 3 of 3

Disconnect and remove the SATA data and power cables from the logic board.

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Step 64

Remove the four 12 mm T10 shoulder screws from the spring plate behind the CPU.

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Step 65

Remove the spring plate from behind the CPU heat sink.

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Step 66

Lift and remove the backing plate from behind the CPU heat sink.
The backing plate has two posts that fit into alignment holes in the logic board and heat sink.

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Step 67

Remove the three 12 mm T8 Torx screws securing the GPU heat sink to the logic board.
Remove the three springs left behind.
These springs might come up with the screws; be careful not to lose track of them.

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Step 68

Lift and remove the heat sink up off the logic board.
The CPU will most likely detach with the heat sink, so be careful about where you lay it down.

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Step 69 CPU

iMac Intel 21.5" EMC 2544 CPU Replacement, CPU: step 69, image 1 of 2

iMac Intel 21.5" EMC 2544 CPU Replacement, CPU: step 69, image 2 of 2

The CPU will most likely be stuck to the heat sink with thermal compound.
Insert the flat edge of a spudger between the CPU and heat sink.
Gently pry the CPU off the heat sink by slightly twisting the spudger upwards.

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Step 70

Remove the CPU from the heat sink. Be careful not to touch the contacts.
To install a new CPU, see our thermal paste guide for instructions on cleaning and preparing the thermal surfaces and applying a new layer of thermal compound onto the CPU and GPU dies.

Edit

Conclusion

To reassemble your device, follow these instructions in reverse and use our Adhesive Strips Guide to reattach the display glass.

37 other people completed this guide.

Author

with 5 other contributors

Sam Goldheart

Member since: 10/18/12

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538 Guides authored

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10 Guide Comments

I just upgraded my 2544 base model iMac (2.7 i5, 8gb ram, 5400 rpm HDD) with all possible options: 3.1 i7 3770s CPU, 16gb ram and a Samsung EVO 850 SSD. The upgrades all worked perfectly, and were made possible for an amateur such as myself thanks to these amazingly detailed and well photographed instruction guides. I can't tell you how helpful they were to me, and just wanted to thank you and share my success. I am an amateur with no significant experience at all with computers, so I wanted to encourage anyone who is hesitant to get the right tools for the job and get to it! Thanks again!

dtfreelancevideo - Mar 31, 2015 Reply Share

What are the compatible CPUs? Is the 3770s the highest option or is it possible to upgrade to an even faster CPU used in 27in models?

Thanks.

s m - Oct 24, 2015 Reply Share

The i7-3770s is the max. for the 21,5" 2012 late iMac, because of the thermal design.

Thanks iFixit for providing this excellent guide!

opeter1 - Sep 7, 2017 Reply Share

Hello,

thank you for this great guide.

which other CPU could I use to upgrade from 2,7 Ghz i5 CPU?

Is an i7-3770 also possible or will he get too hot? (I am asking, because I cannot find any i7-3770s for under 300€)

thank you

robert - Nov 15, 2018 Reply Share

Use Core i7-3770 3.4Ghz (70€ eBay ) (not 3770s) + HyperX Impact 16Gb 1833Mhz 70€ + SSD Samsung 1TB QVO (trim enable) 95€ - all good, without issue. Same TDP have i7 - 3770K iMAC 2012 now have same power as basic iMac 2019. I’m happy. https://browser.geekbench.com/v4/cpu/130...

Vadim Rotari - Jun 9, 2019 Reply Share

iMac Intel 21.5" EMC 2544 CPU Replacement

Introduction

What you need

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iFixit Member of iFixit

10 Guide Comments

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