iMac 2017 27" nightmare

[dermoid777*]

So I think I killed my iMac....

Its an 2017 A1419 27 inch

it came with i5 3.8GHz - I wanted to upgrade to an i7-7700, plus 1TB nvme

Got all the parts, watched all the videos

Big day comes - have al my fixit instructions printed out, go through it step by step, have my screws and parts labels all laid out

Opened the screen w/ the fixit cutter wheel - OK done - all adhesive came off OK and was careful with the 2 monitor cables

So took all the items out step by step

down to the logic board

lets just say no video prepared me for the fact that whilst it's really hard to unscrew all 4 CPU screws and all 4 GPU screws, it's downright impossible to put those back without moving the CPU, keeping tension constant and keeping the tension springs held down - you are tightening 4 x screws on either side of the board at the same time - insane - you need 3 pairs of hands!!!

I did my best anyway through a combination of tape, plastic ties and lying on the floor and screwing in from bottom...!

so put it all back together

Did it start up? No Effin way - not a whimper out of it

OK! So take apart again

down to logic board

and yes CPU had moved and was bent at corner

put back in and tried ot power on again - NOPE
so could be the i7 too - bummer
but now of course i am sh___ing it that i damaged the pins

SO - put the original i5 in again
Started with power and fan on full power
but no further


SO looked at pins

yes some bent , one twisted - tried my best to straighten
Put i5 back in - again no boot

SO Logic Board is screw*d

OK - well I need this badly back up and running so bi the bullet and ordered the board from reputable returnable company in UK the book yard. The price is ... a lot. Then add customs and UPS delivery and its €560 - oh my god, cant afford it but got it anyway

so came yesterday - put RAM in, put bluetooth board on, reinstalled , connected the PSU and was getting 4 diagnostic LED's - great
Then connected screen - power on and....

... no chime, no screen
... look behind screen and LEDs go to 4 (with 4 being half-lit)

try connect keyboard and PRAM reset - nothing
try SMC reset - nothing

screen is black and dead

I know - now I am thinking its the screen but try external display thunderbolt 3 to hdmi on 4K external - and nothing !

and its not chiming either .... which to me is weird

I replaced the PRAM battery
and reseated / tried different configurations of RAM while it was on - nope - no differrence

Could it be the hard drive ?
It has the stock NVME that it came with

Booting while holding Cmd-R does nothing

Kind of at wits end now .... could it be something shorted on logic board?
Its new and seems to be coming from a reputable source...

It just powers on, fans go to full speed, 4 LED's all light and nothing... so now I'm thinking have broken original logic board, new logic board AND a screen... 🙄😟 I mean that takes some doing. Not happy with myself to say the least. This machine is for my work as a freelancer and I've basically cost myself a huge amount of money I can't afford. Luckily there's no work / data on it but still.... just feel like an idiot.

Anyone ever seen this where you have 4 LED's and no chime / no OS boot...?

ALL help suggestions welcome !

 

[Nguyen Duc Hieu]

Buy another working iMac and DO NOT open it ever.

 

[wilberforce]

Buy another working iMac and DO NOT open it ever.

If that is what Hieu says, who is experienced and helpful in repairing iMacs, I think you are in trouble, unfortunately

 

[dermoid777*]

If that is what Hieu says, who is experienced and helpful in repairing iMacs, I think you are in trouble, unfortunately

Thanks for taking the time to reply - would that I could buy a new one. So the lesson is never try.

 

[rpmurray]

Actually, the lesson should: Don't try unless you have a backup machine. I normally don't try to do these kinds of upgrades unless the followng conditions are met:

1. It is out of warranty.
2. I've just bought a new computer so the one I'm working on is now a spare and won't affect me if things go wrong.
3. Upgrading just one part at a time. Test after each upgrade. You're just looking for trouble if you try to jump ahead and do everything at once.

Disclaimer: I have sometimes been known to ignore step one when I get impatient and allow my desires to overrule my reason.

 

[Fishrrman]

Time to start shopping for a replacement.

And a hint:
DON'T try to open and "upgrade" the next one...

 

[wilberforce]

Thanks for taking the time to reply - would that I could buy a new one. So the lesson is never try.

I don't think the lesson is never try ( although I get the quote). I try lots of repairs to all sorts of things myself, and occasionally screw up, which is OK.

I think the lesson is to consider the downside, i.e., what you have to lose, the chance of losing it, and be prepared to accept the loss (i.e., be mentally and financially able to buy a replacement if it goes horribly wrong.)

Another trap is spending more and more to fix it. At some point you are throwing good money after bad, and instead just have to cut your losses and quit.

If there is little to lose and lots to gain, then go for it.

 

[ThrowerGB]

I don't think the lesson is never try. I try lots of repairs to all sorts of things myself, and occasionally screw up, which is OK.

I think the lesson is to consider the downside, i.e., what you have to lose, the chance of losing it, and be prepared to accept the loss (i.e., be mentally and financially able to buy a replacement if it goes horribly wrong.)

Another trap is spending more and more to fix it. At some point you are throwing good money after bad, and instead just have to cut your losses and quit.

If there is little to lose and lots to gain, then go for it.

And don't forget the cardinal rule. BACKUP - BACKUP - BACKUP. Make suer you have a backup of ALL of your system before starting any repair. I fact, make two and keep them in different places.

 

[T Coma]

Buy another working iMac and DO NOT open it ever.

Peak MR.

“I can’t answer your question / help you out in your current situation, but I can tell you what you should have done, or (in case you can’t travel back in time) give purchasing advice like money isn’t a thing.”

 

[wilberforce]

nvm

 

[GloatGoat]

Peak MR.

“I can’t answer your question / help you out in your current situation, but I can tell you what you should have done, or (in case you can’t travel back in time) give purchasing advice like money isn’t a thing.”

You may want to check out Hieu's many helpful posts on MR, he has more experience tinkering with Mac's than most. He gave the OP sage advice, sometimes it's best to cut your losses.

 

[dermoid777*]

Thanks for the replies - Yeah I can see now that I should have been more prepared to accept the consequences I suppose. I think the reason why I thought it was possible was b/c I used to open macs and upgrade them all the time however that was on Intel Mac Pro's / older models - I wasn't ready how irreversible it was going to be and unfortunately no youtube video really will show you that. Will keep trying to get it fixed but as you say good money after bad is an issue.. thanks again for responses though

 

[macguru9999]

well, just talking generally now. you definitely killed the first mobo so unless you could straighten the pins its gone. what about the second one ? did you take care of the pins on that ? did you seat the processor correctly ? did you try both processors ? though i guess if you seated it wrong then that means more bent pins ! and dont blame the screen, an imac will boot and chime with no screen attached so its not that ...

 

[NC_Bulldog]

Anyone ever seen this where you have 4 LED's and no chime / no OS boot...?

ALL help suggestions welcome !

I have done several successful iMac upgrades not involving a CPU upgrade. However, I pretty much duplicated your experience with a recent iMac CPU upgrade because of that very difficult to reinstall CPU retainer bracket.

I also bent the CPU pins and had to replace the MB and CPU. Fortunately in the end I was able to bend the pins back and get the original MB to work. Along the way I also managed to damage the big connector between the LCD and MB. Fortunately it was about $15 to replace it.

With the four lights on and no boot chime I would consider a possible problem with the RAM or SSD. The iMac checks those first, I think, before the LCD turns on. With the SSD on the underside of the MB it is time consuming to easily access it so try changing the RAM around first. Even try just one stick. If it's not the RAM, then the next culprit is the SSD.

Good luck. I know how you feel!

 

[dermoid777*]

well, just talking generally now. you definitely killed the first mobo so unless you could straighten the pins its gone. what about the second one ? did you take care of the pins on that ? did you seat the processor correctly ? did you try both processors ? though i guess if you seated it wrong then that means more bent pins ! and dont blame the screen, an imac will boot and chime with no screen attached so its not that ...

Thanks for that - for the second motherboard CPU/GPU was included so did not have to go near the sockets - just reinstalled in the iMac. Hmm .. if the iMac will boot and chime w/no screen then i'm not sure why it won't boot... I have power and fan spin but that's all even when connected to external display.

 

[dermoid777*]

I have done several successful iMac upgrades not involving a CPU upgrade. However, I pretty much duplicated your experience with a recent iMac CPU upgrade because of that very difficult to reinstall CPU retainer bracket.

I also bent the CPU pins and had to replace the MB and CPU. Fortunately in the end I was able to bend the pins back and get the original MB to work. Along the way I also managed to damage the big connector between the LCD and MB. Fortunately it was about $15 to replace it.

With the four lights on and no boot chime I would consider a possible problem with the RAM or SSD. The iMac checks those first, I think, before the LCD turns on. With the SSD on the underside of the MB it is time consuming to easily access it so try changing the RAM around first. Even try just one stick. If it's not the RAM, then the next culprit is the SSD.

Good luck. I know how you feel!

Thank you so much - it's really helps to hear other people have been through this!

So yeah I thought the SSD / RAM night be the issue too - Using the replacement undamaged Logic Board I put the original NVME back in, reseated the RAM using the stock iMac RAM that came w/the machine.. tried just 1 stick... tried in ports 1 and 3 only... no go on any of these.

I've got some tentative assurance from a logic board repair place in the UK that they can fix the pins on the original board so have my fingers & toes crossed there ...

I have actually returned the replacement "working" Logic Board now ... if the repair guy cannot fix then putting further money in would be unwise .. I mean the reason that I wanted the CPU upgrade in was because I was fairly unimpressed w/ the speed of the i5 cpu... I have a 2014 MBPro (i7 4770) and it honestly seems faster than that 2017 iMac sometimes ... ! 🤷🏻‍♂️

It's true you have the 5K screen (and thats main reason for buying ) ... however if that also needs repair/replacement (though would be great if it's just a damaged LCD cable) surely would be best put that money into a M1 MBPro.... even if I get refund cleared I have still lost €150 on customs charges/UPS so far and it will be another €200 I would say to repair the original board... so it's al mounting up.

The only consolation is that the iMac was a great deal when I bought it.. but I seem to be paying for that now... cuh.

Thanks again for the replies.

 

[rpmurray]

“I can’t answer your question / help you out in your current situation, but I can tell you what you should have done, or (in case you can’t travel back in time) give purchasing advice like money isn’t a thing.”

You make that sound like it's a bad thing.

It's like that brand new 14TB spinner I bought a few months back that I had all formatted and ready to go and then accidentally knocked it off a table. I knew as soon as I heard it hit the floor that it was a goner. Being stubborn, overoptimistic and a masochist I went ahead and tested it and confirmed that I was an idiot. I'm just recounting that here so people can get some amusement from my misfortune.

 

[netsrot39]

I can really relate to the OP’s story, even more than three years later. Last December, I unfortunately “murdered” my 27" iMac Mid-2017 (top-tier model), which had been a gift from a friend. That machine was the best of its line (i7-7700K with Radeon Pro 580). I had upgraded it to a 1 TB PCIe SSD and 64 GB of RAM back in 2023, so it was a really neat machine. Unfortunately, the Verbatim SATA SSD (the second drive in the machine) died a slow death after a few months and started causing Kernel Panics. From that moment on, I knew I would eventually have to open the machine again.

On December 7th, I finally attempted the “surgery” (over a year after the Verbatim SSD started acting up). I managed to separate the display from the chassis perfectly the first time (in 2023), but I completely messed up the second attempt and tried prying the glass with a spudger. After hearing the glass crack, I was devastated—the best part of that iMac was gone.

On December 16th, I found a local ad for a 2015 base-model 27" iMac 5K, which I bought for €100. My goal was to harvest the screen to replace my broken 2017 one (luckily, the screens are cross-compatible). Fortunately, I managed to remove the 2015 screen without any damage.

On December 26th, I tried to reassemble the machine. The Verbatim SSD went straight to the trash and I replaced it with a high-quality Intel enterprise SATA SSD. For some reason, I thought replacing the thermal paste might help, since I remembered the machine getting really hot for no obvious reason. For example, after startup, before the fans kicked in, the i7 was nearly 100°C. My big mistake was removing the heatsink. In my opinion, reinstalling the CPU correctly on that machine is impossible because Apple’s LGA1151 socket lacks a proper retention mechanism. Unsurprisingly, I bent the i7-7700K in two corners where the notches are. The clamp on the other side is a nightmare to handle, and the RAM cage makes things even more difficult.

In early January, I sourced an i7-7700 (non-K variant) cheaply and attempted it again. I bent the clamp slightly with pliers to reduce the force applied. Ultimately, I never got it right. When the CPU was installed, the board only showed two LEDs (the first two LEDs), meaning it didn’t recognize the CPU. Neither the CPU nor GPU were heating up. On closer inspection, I noticed one pin had no head anymore. According to a pinout I found online, it’s the PROC_TRIGIN pin. ChatGPT told me the pin isn’t crucial… but it doesn’t even matter anymore—I still couldn’t get the logic board to recognize the i7-7700. My i7-7700K is dead, and the same problem occurs if I reinstall it. At that point, I gave up on the machine.

Well, not entirely. I managed to source a base-model 2017 iMac 5K i5 logic board from someone converting his iMacs to external displays. Believe it or not, I only paid €20 for the replacement board. I moved my PCIe SSD and 64 GB of RAM to this board. I did not attempt to change the CPU. The i5 is weaker than my original i7 setup, but at least it works. On the bright side, the machine has been very cool—I’ve barely seen it reach 70°C.

So, long story short:

I originally had a perfectly working 2017 iMac 5K with an i7-7700K and Radeon Pro 580. From that machine, I “murdered” the screen, the CPU, and possibly the logic board.

What basically remains of that machine are the chassis, speakers, PSU, PCIe SSD, RAM sticks, and AirPort card. On top of that, it now has a 2015 screen (with minor image retention issues) and a base-model 2017 logic board from a completely different machine. In essence, I have a Frankenstein 2017 iMac made from three different machines.

So what I have now is: a 2017 iMac 5K with an i5-7500, Radeon Pro 575, 64 GB of RAM, and my PCIe SSD (and the SATA SSD, of course).

All in all, the machine feels like my original one, since I’m using my SSD and not much seems different. But under the hood, it’s completely different. So yeah—the 2017 27" iMac is great to use but a nightmare to repair or upgrade. In just under a month, I developed a love-hate relationship with it.

My takeaway: Never remove the heatsink on a 5K iMac. In fact, don’t take off the screen unless you absolutely have to. At least in my case, I could somewhat revive the iMac relatively inexpensively, but the process was an ordeal and a bitter experience.

Hopefully, I won’t have to disassemble that hostile machine again for a few years. I honestly don’t know if I would even try again or just leave it alone. Don’t get me wrong—I love tinkering, I’ve upgraded CPUs in more than ten machines in the past (including iMacs from the 2000s), and I’ve never had a single problem… until this 5K iMac. That machine really killed my joy of tinkering.

Attached are a gory picture of my murdered i7-7700K, a photo showing where I moved everything onto the replacement logic board, and a picture of the internals before I finally sealed up my ‘new’ 2017 iMac.

 

[TwoH]

@netsrot39 I'd keep in mind your 7700K isn't a complete write off being bent like that - you can gently use pliers to bend the CPU back straight and I have found 9 times out of 10 it survives absolutely fine (obviously doing this more than once will start to cause issues however).

For CPU upgrades, or general repasting I use a tool like this
Always prioritise getting the CPU on straight, the GPU will be absolutely fine.
Attached are pictures on my process for the more complicated parts of putting the heatsink back. Put the initial metal bracket back on as this will give you pins coming out which will help align the heatsink back into place properly, and then attach the clamp to hold it down in place.
Now place the retention bracket where you can now screw down the bottom right screw half way and then then slightly lift the clamp up the top-side to slide the retention bracket under the clamp so it will keep it in place and help keep the right side from moving because of that initial screw we have put in.
From there you can use your hand and push with a thumb on the bottom left side where a screw will go, to help you think insert the top left screw and screw it all the way - afterwards fully screw down the bottom right screw, and now you may detach the clamp completely and you're free to complete putting the rest back together.

Honestly I may make a video at some point in the future to show my process more clearly as it isn't easy for me to type it up completely.

 

[PaulD-UK]

@netsrot39 "I managed to separate the display from the chassis perfectly the first time (in 2023), but I completely messed up the second attempt and tried prying the glass with a spudger. After hearing the glass crack, I was devastated..."

The first time is easier, because you are separating the original foam-centred double-sided adhesive tape that Apple used.
The recommended pizza wheel cutter cuts through the foam easily.

The second time you are trying to cut into whatever adhesive tape you used to replace the Apple Original adhesive...
If it didn't have the thick foam core of the original tape, then separation is MUCH more difficult... 🙁

 

[netsrot39]

Hi again!

First of all, I really appreciate the instructions given by @TwoH. I’m pretty sure that if you follow his instructions, you’re very likely to succeed with this surgery.

A little story time: remember the guy I was telling you about in my last post (the one who converts iMacs into 5K displays)? Guess what — he messaged me asking if I’d be interested in another logic board, namely an iMac 27" 5K 2017 4.2 GHz with a Radeon Pro 580. Of course I went and picked it up, so I can basically restore my iMac to pretty much its former glory now.

When I was at his place, I noticed the pile of spare parts he has for 5K iMacs. He pretty much threw in two power supplies and five 1TB hard drives for free, but I gave him a tenner for them. The logic board itself was €80 (16 GB of RAM, blade SSD, and wireless included) — a great deal in my opinion.

Now, I actually tried to revive my original logic board and even modified the spring steel bracket on the front of the board with pliers (so that the tension would lessen). But apparently I deformed it too much, because I still couldn’t get the board to POST.

When I told the guy my story, he gifted me a dead Late 2015 logic board that I could cannibalize the CPU spring bracket from. Last weekend, I gave my original logic board one last shot — and guess what? I actually managed to revive it with an i7-7700, which I got some time ago (I’m not really sure about the condition of my original i7-7700K).

How did I pull it off?

In my opinion, there were three things at play:

• An unmodified steel spring bracket (the right pressure is very important for the CPU to be recognized — less is more when fastening this spring!)
• Removing the RAM cage (this makes things a billion times easier — only a couple of screws to undo)
• Mounting the heatsink while the board is in a more or less 90-degree vertical position (you can see both sides and don’t have to flip it over. It’s a bit challenging, but I think you have the most control doing it this way.)

Actually, I removed the CPU after it posted and installed it twice. On my first attempt, I wasn’t very hopeful, so I couldn’t even be bothered to apply new thermal paste. To my surprise, the logic board posted, and I knew I had to mount the CPU properly again with fresh thermal paste (the same applies to the GPU).

Please note that I unfortunately managed to snap off the head of one of the pins of the LGA1151 socket back in December (only half the size of the pin is remaining). So the fact that the board is working flawlessly is really a big surprise to me.

Also, the i7-7700 I have has a dented corner because it fell off the table onto a granite floor some time ago. I stress-tested the CPU for two hours and haven’t run into any problems yet. The temperatures are a dream and similar to my i5 2017 logic board.

Now I have to decide which board to put back into the iMac — not now, though. I’ll wait until I have a week off because I want to take my time and do things properly.

I’ve attached some pictures of the surgery:

Intel i7-7700 installed on my original 2017 board. Can you see the dented corner of the CPU?

Removing the RAM cage makes a huge difference! Thunderbolt ports and Ethernet port masked with Kapton tape for protection because I was testing in a 2015 chassis.

Some paper in between the RAM sticks so that enough pressure is applied to be recognized by the board (quick and dirty test while the RAM cage with support is unscrewed).

Works like a charm again! (And I was about to throw the board away soon! 😅)

 

[TwoH]

Awesome work @netsrot39 - funnily enough I was repasting a 2017 when reading your post. It did remind me of an issue with the 2017 models I'll just chuck a quick warning for in here for everyone on this thread since it is 2017 specific - it looks like you are okay looking at your pictures.

It's an issue they fix on 2019 boards - but a warning to anyone else looking to take apart their 2017 for any reason. Just be very careful when taking the logic board out, specifically at the part I have shown in these pictures, just to the right-side of the microphone cable. Here there are coils on the other side of the board (just next to the ethernet port - the blank black rectangular items) that can very easily come into contact with the screw mount on the chassis, which is very easy to clip and have one or more of the coils torn off the board.

If you do accidentally manage to do this your machine is going to be okay, you will however lose functionality of your ethernet unless you have some soldering skills to reattach the components.

 

[mreg376]

Honestly, you brought yourself a lot of trouble, time spent and expense. I am also doing work on a 2017 27" iMac. One thing I learned with iMacs is not to screw with them if you are using them to produce income. You did not say the machine was defective, the i7 replacement was not going to give much of a performance boost, and if you needed more storage you could have gone external. If its a hobby machine than no one likes to tinker more than me. But if it's a work machine I won't even go near OCLP as that includes reliability and stability reduction -- even if that keeps me on rock solid Ventura.

 

[netsrot39]

Honestly, you brought yourself a lot of trouble, time spent and expense.

I'd agree with you at first, but it was also a learning experience, and now I know the machine inside and out. Perhaps, from my signature, you can tell that this isn't my only machine, so I don't rely on it professionally. What I want to do is understand the basics of how these computers work and get the most out of them. At this point, I know they’re old—some might even say vintage—but they certainly don't lack repairability (although it can be challenging).


Apple Silicon iMacs probably wipe the floor with them, but they’re more locked down, and I refuse to get one because I want a certain degree of control in case something goes wrong and repair is needed. I’m also aware that newer versions of macOS will soon be unsupported on Intel, and I’ll need to switch OS in a couple of years. I do occasionally run Linux on the side, and I have to say it’s not far behind macOS; it just takes a bit more getting used to.

You did not say the machine was defective, the i7 replacement was not going to give much of a performance boost, and if you needed more storage you could have gone external.

The machine ran way too hot for my liking. A CPU shouldn't be anywhere near 100 degrees Celsius for basic to moderate tasks. Yes, CPU-wise, the machine was already maxed out. External storage is easier to set up, but it's slower. Also, in my opinion, that's not the right way to do things if you're planning to run an OS permanently on a machine.

 

[mreg376]

I'd agree with you at first, but it was also a learning experience, and now I know the machine inside and out. Perhaps, from my signature, you can tell that this isn't my only machine, so I don't rely on it professionally. What I want to do is understand the basics of how these computers work and get the most out of them. At this point, I know they’re old—some might even say vintage—but they certainly don't lack repairability (although it can be challenging).


Apple Silicon iMacs probably wipe the floor with them, but they’re more locked down, and I refuse to get one because I want a certain degree of control in case something goes wrong and repair is needed. I’m also aware that newer versions of macOS will soon be unsupported on Intel, and I’ll need to switch OS in a couple of years. I do occasionally run Linux on the side, and I have to say it’s not far behind macOS; it just takes a bit more getting used to.



The machine ran way too hot for my liking. A CPU shouldn't be anywhere near 100 degrees Celsius for basic to moderate tasks. Yes, CPU-wise, the machine was already maxed out. External storage is easier to set up, but it's slower. Also, in my opinion, that's not the right way to do things if you're planning to run an OS permanently on a machine.

Oops I thought I was referring to the OP, who said the machine was needed for his freelance work.

I don't really disagree with you, if you can afford a machine's down time. My 27" is the 2017 i7 4.2Ghz (which replaced a 2007 24"), and it also runs hot sometimes. But if they have been successfully running hot for 9 years I wouldn't worry about it now. 🙂

I think it's hard to commit to "run an OS permanently," unless you're able to freeze in time your software needs. That being said, I like the 27" and also want to keep it running as long as possible, since the idiots only sell a 24" now. I have upgraded to 64GB, and that helps. Still feels pretty zippy, and I'm not ready to spend $3,000+ on a Mini/Studio Display system. I also have an M1 Max Macbook Pro, but I've never really been a fan of using portables.