iMac Intel 21.5" EMC 2428 CPU Heat Sink Replacement

Replace the CPU heat sink in your iMac Intel 21.5" EMC 2428.

Is your CPU overheating? Replace the heat sink and restore your CPU to its optimal temperature.

Edit Step 1 Access Door  ¶ 

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Edit Step 1 Access Door  ¶ 

  • Lay your iMac face-down on a soft, clean surface as shown.

  • Be sure there isn't any dirt or debris on your work surface, as it may scratch the glass panel on the front of your iMac. We recommend placing a towel between the iMac and the work surface.

  • Loosen the three Phillips screws securing the access door to the bottom edge of your iMac.

  • All three screws will remain captive in the access door.

  • Remove the access door.

Edit Step 2 RAM  ¶ 

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Edit Step 2 RAM  ¶ 

  • Gently slide the black plastic RAM pull tab out from the RAM slot.

  • Pull the black plastic tab away from the bottom edge of the iMac to eject the module(s) on that side of the RAM bay.

  • This may require a bit of force.

Edit Step 3  ¶ 

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Edit Step 3  ¶ 

  • Slide the old RAM module(s) out of their slots in the RAM bay and set them aside.

Edit Step 4  ¶ 

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Edit Step 4  ¶ 

  • Repeat the process in the previous steps to remove the RAM module(s) from the other side of the RAM bay.

Edit Step 5  ¶ 

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Edit Step 5  ¶ 

  • When installing new RAM modules, it is important to orient them correctly.

  • Be sure the small notch cut into each RAM module (shown in the first picture) mates with the protrusion in each RAM slot (shown in the second picture).

  • Your iMac has four RAM slots. Be sure to slide each RAM module into its slot horizontally. This will prevent getting the modules stuck between two of the adjacent slots.

  • Once you have oriented the new RAM modules correctly, gently slide them completely into the iMac and use your thumbs to firmly seat them in their sockets.

Edit Step 6 Glass Panel  ¶ 

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Edit Step 6 Glass Panel  ¶ 

  • Before beginning, unplug your iMac and lay it on a soft surface as shown.

  • Stick a suction cup near each of the two top corners of the glass panel.

  • To attach the suction cups we sell, first position the suction cup with the movable handle parallel to the face of the glass panel. While lightly holding the suction cup against the glass, raise the movable handle until it is parallel with the other handle.

  • If your suction cups refuse to stick, try cleaning both the glass panel and the suction cup with a mild solvent.

Edit Step 7  ¶ 

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Edit Step 7  ¶ 

  • Gently lift the glass panel perpendicular to the face of the LCD enough to clear the steel mounting pins attached along the underside of the top edge of the glass panel.

  • Pull the glass panel away from the lower edge of the iMac and carefully set it aside.

  • During reinstallation, be sure to meticulously clean the inside of the glass panel and the face of the LCD as any dust or fingerprints trapped inside will be annoyingly visible when the machine is turned on.

Edit Step 8 Display  ¶ 

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Edit Step 8 Display  ¶ 

  • Remove the eight 8 mm T10 Torx screws securing the display to the outer case.

  • The last two pictures are detail shots of each side of the display.

Edit Step 9  ¶ 

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Edit Step 9  ¶ 

  • Slightly lift the top edge of the display out of the outer case.

  • Do not lift it too much. There are several cables attaching the display to the logic board.

Edit Step 10  ¶ 

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Edit Step 10  ¶ 

  • Pull the vertical sync cable connector out of its socket on the LED driver board near the top left corner of your iMac.

Edit Step 11  ¶ 

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Edit Step 11  ¶ 

  • Rotate the display out of the outer case enough to disconnect the LED backlight power cable from the LED driver board.

  • Disconnect the LED backlight power cable by depressing the locking mechanism while pulling the connector away from its socket (toward the bottom edge of the iMac).

Edit Step 12  ¶ 

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Edit Step 12  ¶ 

  • Grab the plastic pull tab secured to the display data cable lock and rotate it towards upwards.

  • Pull the display data cable straight out of its socket on the logic board.

  • Do not lift up on the display data cable, as its socket is very fragile. Pull the cable parallel to the face of the logic board.

Edit Step 13  ¶ 

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Edit Step 13  ¶ 

  • Disconnect the LCD thermal sensor cable connector from its socket on the logic board.

Edit Step 14  ¶ 

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Edit Step 14  ¶ 

  • Carefully pull the display toward the top edge of your iMac and lift it out of the outer case, minding any cables that may get caught.

Edit Step 15 Optical Drive  ¶ 

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Edit Step 15 Optical Drive  ¶ 

  • From here, the repair will be easier if you flip the computer around so the base is facing you.

  • Remove the following four screws:

    • One 9.3 mm T10 Torx screw with a large head

    • Three 9.3 mm T10 Torx screws with a normal sized head

Edit Step 16  ¶ 

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Edit Step 16  ¶ 

  • Pull the optical drive thermal sensor connector straight up from its socket on the logic board. Pull parallel to the board.

Edit Step 17  ¶ 

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Edit Step 17  ¶ 

  • Lift the inner edge of the optical drive and maneuver its connector past the GPU frame attached to the logic board.

  • Carefully pull the optical drive off its mounting pins on the right side of the outer case to gain clearance for disconnecting the optical drive cable.

  • Allow the optical drive to hang down as you de-route the optical drive thermal sensor connector from behind the GPU heat sink.

Edit Step 18  ¶ 

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Edit Step 18  ¶ 

  • Disconnect the optical drive cable by pulling its connector away from the optical drive.

  • Remove the optical drive from the iMac.

Edit Step 19 Optical Drive Fan  ¶ 

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Edit Step 19 Optical Drive Fan  ¶ 

  • Remove the single 13 mm T10 Torx screw securing the optical drive fan to the outer case.

Edit Step 20  ¶ 

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Edit Step 20  ¶ 

  • Pull the optical drive fan off the pins attached to the outer case.

Edit Step 21  ¶ 

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Edit Step 21  ¶ 

  • Pull the optical drive fan connector away from its socket on the logic board.

  • Remove the optical drive fan from the iMac.

Edit Step 22 Logic Board  ¶ 

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Edit Step 22 Logic Board  ¶ 

  • In the proceeding steps, you will disconnect the following cables:

    • SD Board

    • Left/Right Speaker and Microphone

    • Audio Port

    • Wi-Fi Antenna

    • Right Temperature Sensor, Bluetooth/Ambient Light Sensor/Camera/Left Temperature, and Hard Drive Fan

    • CPU Fan/Ambient Temperature and Power Button

    • IR Sensor

Edit Step 23  ¶ 

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Edit Step 23  ¶ 

  • Pull the SD board cable out of its socket on the logic board.

Edit Step 24  ¶ 

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Edit Step 24  ¶ 

  • Disconnect the microphone, left speaker, and right speaker cables by pulling their connectors toward the right side of the iMac.

Edit Step 25  ¶ 

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Edit Step 25  ¶ 

  • Use the flat end of a spudger to pry all three AirPort antenna connectors up from their sockets on the AirPort board.

  • During reinstallation, connect the cable with no stripes to the socket marked CH0, the cable with one stripe to CH1, and the cable with two stripes to CH2.

Edit Step 26  ¶ 

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Edit Step 26  ¶ 

  • Pull the hard drive fan connector toward the top edge of the iMac to disconnect it from its socket on the logic board.

Edit Step 27  ¶ 

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Edit Step 27  ¶ 

  • Use your thumbnails on both sides of the Bluetooth/ambient light sensor/camera/left temperature connector to push it toward the top edge of the iMac and out of its socket on the logic board.

Edit Step 28  ¶ 

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Edit Step 28  ¶ 

  • Use your thumbnails to push the right temperature sensor connector toward the top edge of the iMac and out of its socket.

Edit Step 29  ¶ 

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Edit Step 29  ¶ 

  • Pull the CPU fan/ambient temperature sensor connector toward the bottom left edge of the iMac and out of its socket on the logic board.

Edit Step 30  ¶ 

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Edit Step 30  ¶ 

  • Pull the power button connector toward the bottom left corner of the iMac to disconnect it from its socket on the logic board.

Edit Step 31  ¶ 

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Edit Step 31  ¶ 

  • Use your thumbs to push the IR sensor connector toward the top edge of the iMac and out of its socket on the logic board.

  • Pull the IR sensor board up from behind the front face of the outer case.

  • Remove the IR sensor and set it aside.

Edit Step 32  ¶ 

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Edit Step 32  ¶ 

  • Pull the audio port cable connector toward the left side of the iMac to disconnect it from the logic board.

  • Do not pull the cable toward yourself (away from the front face of the logic board) as you disconnect it.

  • Peel the audio port cable off the front face of the logic board and let it hang down as shown in the second picture.

Edit Step 33  ¶ 

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Edit Step 33  ¶ 

  • Remove the following seven screws:

    • Two 7 mm T10 torx screws

    • One 30 mm T10 Torx screw

    • Two 25 mm T10 Torx screws

    • Two 21 mm T10 Torx screws

Edit Step 34  ¶ 

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Edit Step 34  ¶ 

  • Remove the following four screws:

    • One 9.3 mm T10 coarse-threaded screw

    • One 25 mm T10 coarse-threaded screw

    • Two 22 mm fine-threaded screws

  • Pull the upper right and lower left corners of the power supply away from the rear case to dislodge the mounting posts attached to the power supply's corners.

Edit Step 35  ¶ 

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Edit Step 35  ¶ 

  • Carefully lift the power supply out of the outer case and rotate it to expose the cable lock as shown, minding the DC-out and AC-in cables still attaching it to the iMac.

  • Disconnect the DC-out cable by depressing the locking mechanism on the connector while you pull the connector away from its socket on the power supply.

  • Once the locking mechanism has cleared the socket, pull the DC-in connector away from the power supply.

Edit Step 36  ¶ 

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Edit Step 36  ¶ 

  • Disconnect the AC-In cable by depressing the locking mechanism while pulling the connector away from its socket.

  • Remove the power supply from the outer case.

Edit Step 37  ¶ 

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Edit Step 37  ¶ 

  • Remove the plastic wall that is installed directly to the right of the LED driver board.

Edit Step 38  ¶ 

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Edit Step 38  ¶ 

  • Slightly pull the logic board away from the back of the outer case, then lift it upward to clear the lower front face of the outer case.

Edit Step 39  ¶ 

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Edit Step 39  ¶ 

  • Disconnect the LCD temperature cable by pulling its connector up and out of its socket on the logic board.

Edit Step 40  ¶ 

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Edit Step 40  ¶ 

  • Depress the locking mechanism and carefully pull the DC-In cable out of its socket on the back of the logic board.

Edit Step 41  ¶ 

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Edit Step 41  ¶ 

  • Being careful not to damage the socket on the logic board, gently pull the hard drive SATA data cable straight out of its socket on the logic board.

Edit Step 42  ¶ 

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Edit Step 42  ¶ 

  • Pull the hard drive power cable connector out of its socket on the logic board.

Edit Step 43  ¶ 

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Edit Step 43  ¶ 

  • Remove the logic board from the outer case, minding any cables that may get caught.

  • When reinstalling the logic board, plug in a thunder port cable and a USB cable into the outer USB port before tightening the logic board screws to ensure proper alignment.

Edit Step 44 CPU Heat Sink  ¶ 

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Edit Step 44 CPU Heat Sink  ¶ 

  • Peel the piece of tape covering the heat sink thermal sensor cable up off the logic board.

Edit Step 45  ¶ 

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Edit Step 45  ¶ 

  • Lift the heat sink thermal sensor connector straight up out of its socket on the logic board.

  • Make sure to pull only on the connector and not the socket itself.

Edit Step 46  ¶ 

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Edit Step 46  ¶ 

  • If present, remove the "Warranty void if removed" sticker covering one hidden screw on the heat sink.

Edit Step 47  ¶ 

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Edit Step 47  ¶ 

  • Remove the following five screws securing the heat sink to the logic board:

    • Four 6.4 mm T8 Torx screws

    • One 4.3 mm T10 Torx screw

  • It may be necessary to hold the socket with a Phillips screwdriver on one side of the board while you unscrew the Torx screw on the other side of the board.

Edit Step 48  ¶ 

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Edit Step 48  ¶ 

  • Carefully lift the logic board off the heat sink.

  • If the two components appear stuck together, carefully pry them apart with the flat end of a spudger, being careful not to disturb any surface-mount components on the logic board.

  • Make sure to apply a new layer of thermal paste before reattaching the heat sink. Our thermal paste guide makes it easy.

To reassemble your device, follow these instructions in reverse order.

For more information, check out the iMac Intel 21.5" EMC 2428 device page.

Required Tools

TR8 Torx Security Screwdriver

$5.95 · 50+ In stock

Spudger

$2.95 · 50+ In stock

TR10 Torx Security Screwdriver

$1.95 · 50+ In stock

Heavy-Duty Suction Cups (Pair)

$14.95 · 50+ In stock

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Comments Comments are onturn off

Before beginning unplug your iMac.

Henry Barnett, · Reply

i pulled very hard on this tab, could not get it to release?

is this common?

Arjun Govindjee, · Reply

It is far harder than I thought you have to pull REALLY hard and then there will be a little click and than you can gently pull out the RAM.

Alison Newton , · Reply

When reinstalling RAM in this machine or any iMac with upgradable RAM slots push hard to get them to go in (Apple really did make this one harder than it needed to be). If you don't push hard it won't go in and your computer won't work. (trust me on this learned the hard way)

Robert Wacker, · Reply

Change "Before beginning, unplug your iMac and lay it on a soft surface as shown." to "Lay your iMac on a soft surface as shown"

Henry Barnett, · Reply

my imac power sullye not powering

tahir, · Reply

imac 2544 2.5 core i5 i touched the motherboard to supply and it spark now it is not powering

please tell me the directions

thanks witting for answering .

tahir, · Reply

Im sorry to say, If it sparked when you touched it your motherboard s now fried. You need a new one.

Robert Wacker,

Very easy to lift the glass out. Don't jerk too hard.

kctipton, · Reply

Success replacing the stock ST31000528AS with a STBD3000100 (Dead 1TB to new 3TB, both Seagate). First try. Using another Mac and a quality Firewire 800 cable, I formatted it using Target Disk mode, 2 partitions (defaults, except I made the first one bigger than the second). To the second, smaller one, I copied a bootable Install OS X Mavericks partition. Tried to boot. It booted, and I installed; nary a glitch. (Running the Installer over Firewire would have been faster, but I didn't want to reboot this machine.)

See part 2 below...

Matthew Elvey, · Reply

(Part 2:)

I SKIPPED steps 6, 7 AND 8! Instead, after doing Step 5, I noticed I then had enough room and cable length to access the screws in Step 11 if I lifted the LCD up an inch or so, rotated it about 20-30 degrees clockwise and moved it a couple inches toward the base, and put it down. After removing them (Step 11), I propped up the LCD (with a spare spudger) and had enough room to do Steps 12, 13, and 14 without much difficulty. Felt safer/less work and risk than not skipping steps 6-8. No risk of the damage Ersan and Michael caused performing Step 7!

Matthew Elvey,

I just edited that step to add a note about the shortcut.

Matthew Elvey,

What the ???

Geoff Wacker has REJECTED my edit: https://www.ifixit.com/Guide/history/ste...

I wonder why. What's the deal, Geoff? I mean I'd understand if I suggested folks didn't need the suction cups, as that could cut into iFixit's income stream, but what's wrong with suggesting that a few steps aren't needed? It worked for me; the EMC 2389 I fixed is humming along with a new 3TB HD I installed while skipping those steps.

Matthew Elvey,

I did not have to remove a single cable! After undoing the torx screws from the sides, I was able to rotate the LCD out of the way enough to reach all the screws holding in the ODD bracket. One of them was a bit challenging to get to, but I never felt that I was risking the cables by leaving them connected. Also, it wasn't totally clear, but you have to actually remove the ODD itself from the ODD bracket - 4 torx screws. The SDD mounts into the hard drive enclosure, then the enclosure is screwed into the bracket. Those holes (enclosure <-> Bracket) did not line up correctly for me, and I had to go with only three of them connected in the end. Seems to work fine.

cdansmith1, · Reply

Another comment on DATA & LCD Temp. Sensor cables: I had to remove the vertical sync, and the backlight cable, however, if you have an assistant or/can carefully rotate the screen clockwise/and then have it held up about 5" to 6" at a slight angle, you do not need to remove LCD data cable or LCD thermal cable, however - IMPORTANT: you must have a second pair of hands/or way to securely prop up the LCD. Also, don't rotate too much, since then you will pull out LCD data cable, and it renders the whole exercise moot, or can damage the cable or connector.

MaximBorzov, · Reply

You don't need suction cups. The screen, held by magnets, can simply be pried off using a very thin blade such as a screw driver and fingers.

Deepsurvival, · Reply

The metal near the screws is VERY magnetic. Honestly, the hardest and by far most frustrating step was trying to put these screws back in.

seancourtney, · Reply

I ran into the same problem - easily the most frustrating part of this process. To help deal with it, I took a drinking straw, cut it to be about 2 inches long, and used it as a chute to guide the screw to the hole. Dropping the screw down the straw, it'd still stick to the side due to the magnets, but using my screwdriver, it was easy to push the screw down to where it needed to go, and the straw kept the screw from being pulled out of place by the magnets.

josh,

You can use one hand to hold the edge up while reaching with the other hand to disconnect cables. You may want to have a prop handy (like a small book) or an extra person to hold the edge up while you disconnect cables.

kctipton, · Reply

I am having a difficult time reattaching the LCD cable. A better description or any tips would be useful here.

Ben Bauermeister, · Reply

When putting the display down on the table, be careful not to kink the flat ribbon cable.

frank, · Reply

The replacement hard drive I used doesn't even appear to spin up and the Time Capsule restore process doesn't show it as available. It just stays at Searching for disks and never finds it.

JRBv3, · Reply

I had to use Disk Utility to partition the drive and then it showed fine. Rookie mistake.

JRBv3,

In my case the red screw was on the lower left side near the power-data cable!

at3mlos, · Reply

Mine has these cables exactly opposite what is shown here. (?)

Danno, · Reply

same with mine

andriivarko,

You forgot after this step to pull out the optical drive cable from the mlb, also make it very clear that its crucial to put those cables back in the right socket not to cause bigger damage to the logicboard.

davis 12, · Reply

4+1 = 5

You say "remove 6 screws".

anne guillaume, · Reply

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