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This teardown is not a repair guide. To repair your iMac Intel 21.5" Retina 4K Display (2017), use our service manual.

  1. iMac Intel 21.5" Retina 4K Display 2017 Teardown, iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 1, image 1 of 2 iMac Intel 21.5" Retina 4K Display 2017 Teardown, iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 1, image 2 of 2
    • Well this exterior certainly isn't giving much away, but you can't always judge a book by the aluminum-and-glass shell of the iMac that you're reading it on. Let's start with what we know:

    • 3.0 GHz quad-core Intel Core i5 (Turbo Boost up to 3.5 GHz)

    • 8 GB of 2400 MHz DDR4 memory

    • Radeon Pro 555 GPU with 2 GB of VRAM

    • 1 TB (5400-rpm) hard drive

    • 802.11ac Wi-Fi and Bluetooth 4.2

    • 43% brighter display (500 nits) with 4096 × 2304 resolution and P3 wide color gamut

  2. iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 2, image 1 of 2 iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 2, image 2 of 2
    • A peek at the back reveals a bevy of ports. First, the usual suspects: a headphone jack, SD card reader, four USB ports, and an ethernet jack.

    • The un-usual suspects? This iMac's sporting two Thunderbolt 3 ports. These support double the bandwidth of the previous generation—each of these ports can push data at 40 Gbps.

    • That's enough throughput to drive four 4K external monitors—although with this hardware configuration, Apple says we're limited to two.

    • How are we supposed to get by with a total of just three 4K displays? How?

    • Confirming our suspicion that this is mostly a 2015 iMac with a facelift, this unit sports the same model number (A1418), but with a new EMC: 3069.

  3. iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 3, image 1 of 2 iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 3, image 2 of 2
    Tool used on this step:
    iMac Opening Wheel
    $7.99
    Buy
    • We grab our pizza cutter iMac Opening Wheel and go to town. Then, we bring it back home and use it to split open our fancy new iMac.

    • 'Round and 'round we go, and the adhesive securing the display perimeter goes kaput.

    • When Apple introduced this form factor in 2012, replacing the much-loved magnets, we were sad and confused. Since then we've learned its secrets, and now we're on board with how easy this adhesive is to slice through.

    • We'd love to see Apple implement something like this in their other product lines.

    • After a familiar opening procedure, we get our first peek inside.

  4. iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 4, image 1 of 3 iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 4, image 2 of 3 iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 4, image 3 of 3
    • With all the glass and pixels out of the way, we immediately pick out some subtle updates.

    • First, the logic board has grown—encroaching on territory formerly held down by the right speaker, and even expanding towards the fan a bit.

    • Even more notable, there's a conspicuous heat sink mounting plate sprawled out in the middle of the board. Funny, the old heat sink didn't need one of those...

    • Lastly, near the center of the bottom display bezel, just beneath the glass, there's a microphone! Whose ribbon cable routes right over the top of a screw, which is pretty weird.

  5. iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 5, image 1 of 1
    • Well, this part of the refresh is less refreshing than we'd like—the right speaker is no longer immediately removable. It's trapped pretty solidly by the new logic board contours.

    • No big deal; it just means your favorite set of iMac repair guides won't fully apply to this model. We'll get to work on that for you.

  6. iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 6, image 1 of 2 iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 6, image 2 of 2
    • The rest of this iMac comes apart pretty much the way we expect, and we dispense with the power supply, hard drive, and fan without fuss.

    • And with a bit more elbow grease, we shimmy the logic board out of its slot to reveal ... removable RAM? We can hardly believe our eyes.

    • Yep, those are SO-DIMMs. Two of them.

    • Slightly less excitingly, there's also an exciting split heat sink. But seriously, look at that RAM!

  7. iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 7, image 1 of 2 iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 7, image 2 of 2
    • It may not be as accessible as the (dead simple) RAM hatch found in the 27" iMacs—but still, this is a major win for upgradability over all the 21.5" iMacs with soldered RAM that we've encountered in recent years.

    • Before moving on, we take a moment to scope out the silicon these memory modules have to offer:

    • SK Hynix H5AN8G6NAFR-UHC 8 Gb DDR4 SDRAM (4 × 8 Gb = 4 GB per DIMM, 8 GB total)

    • Ablic (formerly Seiko Instruments) S-24C04A 4 Kb Serial EEPROM Memory

  8. iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 8, image 1 of 2 iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 8, image 2 of 2
    • This new heat sink design has us intrigued. What's hiding under there?

    • Warranty voiding stickers on the heat sink screws? That's odd. Could that mean...

    • Yes! The CPU is modular, too! It lifts right off with the heat sink, revealing a standard LGA 1151 CPU socket.

    • Again, this isn't the most accessible thing in the world—it's flipped onto the backside of the logic board, trapped behind a lot of other components, and buried under a glued-down pane of glass—but for the first time in years it's possible to replace or upgrade the CPU without a reflow station, and that's a big win.

  9. iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 9, image 1 of 2 iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 9, image 2 of 2
    • This CPU is quite well thermally-pasted into its heat sink; prying it out was surprisingly tough. Someone wants this processor to keep cool.

    • Finally, we're face-to-face with the star of this teardown: an Intel SR32W Core i5-7400 Kaby Lake CPU, 6M Cache, up to 3.50 GHz.

    • Looking at the rest of the Kaby Lake lineup, we're actually not seeing any desktop-class CPUs in a BGA package. Maybe Apple reverted to a socketed CPU because that's all Intel is offering at the moment.

    • But with Apple's clout and famous negotiating skills, you'd think they could get a soldered CPU if they wanted. Plus there's that mysterious modular RAM...

    • Have you been hearing our pleas, Apple?

  10. iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 10, image 1 of 1
    • The final bit of interesting modularity on this board: a CMOS battery.

    • With all this new modular hardware, it almost looks like they ran out of space for this guy. It's hilariously placed vertically in this cute little battery toaster slot.

    • Side note: please do not put batteries in the toaster.

    • Or toast in your iMac for that matter...

  11. iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 11, image 1 of 1
    • Now that it's stripped of all accoutrements, we can ID this logic board's silicon:

    • Intel LGA 1151 CPU socket

    • AMD Radeon Pro 555 GPU

    • SK hynix H5GC4H24AJR-ROC 4 GB GDDR5 2400 MHz SDRAM (4 GB × 4 for a total of 2 GB VRAM)

    • Broadcom BCM5776 Gigabit Ethernet controller

    • Texas Instruments CD3215C00 (also seen recently in the 15" MacBook Pro) USB type-C controller

    • Intel SR2C9 platform controller hub

  12. iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 12, image 1 of 1
    • Flip the board for more chips? Don't mind if we do:

    • Vimicro VC0359 camera processor

    • Cirrus Logic CS42L83 audio codec

    • MXIC MX25L6473E 64 MB serial flash memory

    • Intersil ISL95828 Intel CPU PWM controller

    • NXP Semiconductor CBTL06142E display port multiplexer (likely)

    • Intersil ISL6277A multiphase PWM regulator

    • Fairchild FDH10CJ MOSFET

  13. iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 13, image 1 of 2 iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 13, image 2 of 2
    • Chip identification, continued:

    • Texas Instruments LM4FS1EH system management controller

    • Texas Instruments TAS5764L audio amplifier

    • Intel JHL6540 Thunderbolt 3 controller (likely)

    • Dialog Semiconductor (formerly Adesto) AT45DB021E 2 MB serial flash memory

    • Winbond W25Q80DW 8 MB serial NOR flash memory

    • Macronix MX25L1006E 1 MB serial NOR flash memory

    • Texas Instruments TMP423 triple remote/local temperature sensor

  14. iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 14, image 1 of 2 iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 14, image 2 of 2
    • Chip identification, continued:

    • Fairchild FDMF5804 smart power stage

    • International Rectifier IRF3575 60 A synchronous buck controller

    • Texas Instruments LP8565A128 MOSFET driver

    • Renesas (formerly Intersil) ISL62383C notebook power supply controller

    • Texas Instruments REF3330 3.0 V voltage reference

    • Texas Instruments TPS3897 1-channel voltage supervisor

    • Texas Instruments TPS3847108 380 nA voltage monitor

  15. iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 15, image 1 of 2 iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 15, image 2 of 2
    • Chip identification, continued:

    • Texas Instruments INA210/INA213/INA214 current sense amplifier, OPA348 operational amplifier, and TLV3701 high-voltage comparator

    • Texas Instruments TPS51916 memory power supply

    • Texas Instruments TPS54622 6 A synchronous buck converter

    • Texas Instruments TPS62130B 3 A step-down converter

    • Texas Instruments TPS2557/TPS22990/TPS22966 Load Switches

    • Texas Instruments SN74LVC08A and Nexperia (formerly NXP Semiconductor) 74LVC08A 4-channel, 2 input AND gate

    • Nexperia (formerly NXP Semiconductor) 74LVC1G99 3-state configurable function gate

  16. iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 16, image 1 of 1
    • Turning our attention back to the display: the fancy new panel comes courtesy of LG (who also made the fancy old panel).

    • And that famously W-Fi allergic external monitor...

    • This particular ultra-high def beauty is model LM215UH1-SDB1.

    • Now moving to the display chips, read on!

  17. iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 17, image 1 of 3 iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 17, image 2 of 3 iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 17, image 3 of 3
    • Take a peek at what powers those popping pixels:

    • Texas Instruments SN74LVC8T245 8-bit dual-supply bus transceiver

    • Texas Instruments BUF16821 programmable gamma-voltage generator and Vcom calibrator

    • Parade Technologies DP665 LCD timing controller (the same found in the last generation iMac 4K)

    • We assume this is an Apple modified version of the DP663

    • Texas Instruments TPS54218 4.5 V to 17 V input, 2 A synchronous step-down SWIFT converter

    • Texas Instruments TPS54320 4.5 V to 17 V input, 3 A synchronous Step-Down SWIFT converter

    • Texas Instruments TPS65168 high resolution, fully programmable LCD bias

  18. iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 18, image 1 of 3 iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 18, image 2 of 3 iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 18, image 3 of 3
    • Display controller board chip identification, continued:

    • Texas Instruments TMP423 triple remote/local temperature sensor

    • Winbond W25Q40CL 4 MB serial NOR flash memory

    • Texas Instruments TPS3808 current supervisor

    • Ricoh R1154N065B 150 mA LDO regulator

    • Texas Instruments SN74AHC1G08 single 2-input AND gate and SN74LVC1G04 dual inverters

    • Texas Instruments SN74LVC1G98 configurable multiple-function gate

  19. iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 19, image 1 of 2 iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 19, image 2 of 2
    • Previous iMacs featured a dual-mic setup, with two microphones hiding behind the front-facing camera. Two microphones allows the device to filter out ambient noise and produce a cleaner signal.

    • This year, it seems Apple switched to a single microphone—and moved it to the bottom of the display, behind the glass.

    • Perhaps they've improved their signal processing enough to make do with one and save some pennies.

    • We'll wait to hear from the early adopters if the new setup is any better or worse.

  20. iMac Intel 21.5" Retina 4K Display 2017 Teardown: step 20, image 1 of 1
    • And that's that!

  21. Final Thoughts
    • The CPU and RAM—two of the components you are most likely to upgrade at some point—are both modular.
    • The standard 2.5" SATA hard drive is fully upgradable—though you can't add a blade SSD thanks to an empty pad on the logic board.
    • Cutting the tape to open the iMac isn't too hard (with the right tools), but it must then be replaced to complete any repair.
    • Most replaceable components (like the RAM) are buried behind the logic board, meaning you'll have to take apart most of the iMac just to gain access to them.
    • The glass and Retina Display are fused together, increasing the cost of replacement.
    Repairability Score
    3
    Repairability 3 out of 10
    (10 is easiest to repair)

78 Comments

You mentioned a 3.5" SATA HDD in "Final Thoughts", but as per the Picture it seems to be a 2.5" as previous models. Can you please confirm. Thanks

musstafaa - Reply

I fixed it right now!

Federico Barutto -

Apple offer Fusion and SSD as BTO options - so the logic board must be different for that surely as you said there is no SSD slot? Another tear down in a few days/weeks!!?

Dominic Cazenove - Reply

The Fusion-Drive and the SSD only versions might have the necessary connector soldered onto the board. At the photo, you will see the screw hole for mounting a Blade SSD.

Michael Slomma -

And you can see where the connector would be soldered at the bottom left of the board.

Dominic Dunlop -

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