iMac (Retina 5K, 27-inch, 2017) CPU and NVME SSD Upgrade Pitfalls and Tips

sebastienc

macrumors newbie
Oct 14, 2019
12
0
I assume you're talking to me? (Just checking--Paul, not Ben. Totally doesn't matter on an internet forum of course; it just confused me as to whether you were asking me or not.)

Anyway, no, no luck at all with my temperature issues, but in my case it's almost certainly the drive. (I haven't messed with the CPU--nowhere near that brave.) I was glad to hear that your system is bootable again, though--I was watching your experiences with a sort of secondhand anxiety! Good luck finishing things up.

I'll get the SSPOLARIS drive soon and hope I'll have a chance to install it within the next few days. Even though the upgrade will leave me with less space than I had originally hoped, it will still be an improvement on my original setup, and I'm ready to be done with this process. I'm just hoping everything goes smoothly.

Re the fan issues, you mention that you haven't fully booted with the LCD on since reinstalling the original CPU. I noticed that earlier in this thread ipadawan discussed booting without the screen installed and mentioned the fans running at full speed as one of the consequences. So it's possible that's not an indicator of real thermal issues, just a side effect of having the case open and the display detached. (Possibly due to missing signal from display temperature sensors?) Seems like when you get the new CPU in it would be worth reconnecting the display and taping it on with painter's tape before reaching any final conclusions about fan problems.

Again, good luck!
Sorry Paul!! Yes this was a message for you!
Thanks for pointing at ipadawan experience.
CPU upgrade, especially because of the spring plate, is quite nerve-racking. Will post again when I'm closer to testing the new CPU.

Here is a picture of the 970 EVO 1TB and Heatsink with the Sintech NGFF. Both worked fine. Too bad it didn't work for you.
IMG_4252.jpeg
 

sebastienc

macrumors newbie
Oct 14, 2019
12
0
I assume you're talking to me? (Just checking--Paul, not Ben. Totally doesn't matter on an internet forum of course; it just confused me as to whether you were asking me or not.)

Anyway, no, no luck at all with my temperature issues, but in my case it's almost certainly the drive. (I haven't messed with the CPU--nowhere near that brave.) I was glad to hear that your system is bootable again, though--I was watching your experiences with a sort of secondhand anxiety! Good luck finishing things up.

I'll get the SSPOLARIS drive soon and hope I'll have a chance to install it within the next few days. Even though the upgrade will leave me with less space than I had originally hoped, it will still be an improvement on my original setup, and I'm ready to be done with this process. I'm just hoping everything goes smoothly.

Re the fan issues, you mention that you haven't fully booted with the LCD on since reinstalling the original CPU. I noticed that earlier in this thread ipadawan discussed booting without the screen installed and mentioned the fans running at full speed as one of the consequences. So it's possible that's not an indicator of real thermal issues, just a side effect of having the case open and the display detached. (Possibly due to missing signal from display temperature sensors?) Seems like when you get the new CPU in it would be worth reconnecting the display and taping it on with painter's tape before reaching any final conclusions about fan problems.

Again, good luck!
@paulbee . Yes, this message was meant for you! Sorry about the name mix up.
Thanks for pointed at iPadawan message. And @TwoH thanks also for your message.
All this is useful. However, I must add some information about my NVMe upgrade: I do plan to add an SSD, but didn't install it this weekend when I reload MacOS onto the NVMe drive and when I did that I had the SSD cable plugged onto the logic board but not connected to anydrive on the other end... No fan issue then.

I'll install the new CPU tonight and post any update I have. Wish me luck.
- - Post merged: - -

About the last post. I closed my browser inadvertently and didn't see my first reply. That's why I've posted another reply...
 

sebastienc

macrumors newbie
Oct 14, 2019
12
0
FINAL UPDATE:
...
Drum roll...
...
I got the sucker to work!

Short update: Metal spring underneath the CPU is the prb. You have to unbend it.

Longer answer:
1. When I pulled the CPU out I saw one corner slightly bent. The mutli-layer PCB is soft, so it's possible to straighten it. It also meant that something was bending it.
Almost all the thermal paste was also squished to the sides. So there was way too much pressure on the CPU.
This also meant that some of the PINs in the corner were not connecting. Thus the Logic board wouldn't boot.
Getting LED 1 or LED 1-2 both means CPU issue. Ultra fan speed also was due to that...

2. I've removed quite a bit of tension from the spring. I spent so many hours in the last few days on that "upgrade", that I got tried and didn't take a picture of the prior. But here is the after:
IMG_4275.jpeg


3. After that not all was smooth, but I got it to boot and I couldn't wait to seal the damn thing. So I just did that... Before realizing that I had forgotten to screw the speakers! Haha.
Well I took out the logic board 4 times. Tested the i7-700K twice. Put the i5-7600 back in. Then installed/uninstalled/reinstalled the i7-7700. So I was ready before seeing it worked to remove the board again, and thus left the speakers loose.

Results:
Great speeds with the NVME and SSD, and I got an 8 threads CPU.
Screen Shot 2019-10-17 at 7.01.59 PM.png
Screen Shot 2019-10-17 at 7.01.08 PM.png


Next steps: Happy to help anyone here with questions. However, I'm not trouble free.
The Samsung EVO 970 run ultra hot!! 75C under mild load. The heatsink touches the housing which I hope will help dissipate some heat, but It's a bit of a worry.

Good luck to anyone still working on their rig!
 

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paulbee

macrumors member
Nov 17, 2011
65
4
The Samsung EVO 970 run ultra hot!! 75C under mild load. The heatsink touches the housing which I hope will help dissipate some heat, but It's a bit of a worry.
Yikes! I wonder how the people who have gotten their 970 Evos running in the 30s-40s have managed to do it. Your temperatures are even worse than mine. (Maybe proximity to your hotter CPU. There was a while where I experimented with running Macs Fan Control to bring my fan speeds down by keying them to CPU temperatures, but without the fan running the Evo would get hot enough that it would spike my CPU temperatures and get the fans racing that way. They're close enough on the board that I guess it makes sense for the temperatures to affect each other.)

Today I tore my system back down, pulled the Evo, and installed a 128 GB SSPOLARIS I bought on eBay that came from a brand new iMac. I had also installed a 1 TB Crucial MX500, and after some consideration I decided I'd set them up as a fusion drive. (Despite some people's maintaining that a two-SSD fusion drive is pointless, the speed difference between the PCIe and SATA interfaces is significant enough that I don't believe that's true.)

My first try at the fusion drive resulted in the drive reading and writing at SATA speeds. Some further exploration proved what I suspected: following Apple's instructions for creating a fusion drive had resulted in my SATA being primary and my NVMe being secondary, even though I had listed the drives in the right order in the commands.

I gave it a second go following the instructions by DaSal in this thread:
How to make an APFS fusion drive (SSD + NVME)

Boot into internet recovery > option CMD R.

Open diskutilty and unmount your drives.

Make sure the drives are ‘fresh’ (not already APFS partitioned, otherwise it will fail), by creating a new HSF filesystem on the drives. (Workaround, but it works, quick and easy.)

diskutil list

Note the disk numbers of the drives you want to use (primary drive (fast drive) and secondary (slow drive). Example: disk0 (fast) and disk1 (slow). Replace examples with your own disk numbers.

diskutil cs create Fusion disk0 disk2

Now that they’re HSF again we can make them into an APFS Fusion drive. Use the commands -main and -secondary to assign which drive will be the fast drive (-main) and which drive the slow drive (-secondary).

For the APFS container we’ll need not just the disk numbers, but the actual partition which contains the bulk of the storage. If you run diskutil list you will see that for instance, disk0s2 might be the actual storage capacity on disk0. Use this in the following commands.

diskutil apfs createContainer -main disk0s2 -secondary -disk2s2

It’ll create an empty APFS container now. (I don’t quite understand how this works so don’t ask me.)

At this point you should be able to add the volumes to the container using addVolume in the terminal, but this didn’t work for me.

Close the terminal and open Disk Utility. Click partition and choose add volume. Create a new APFS volume and give it a nice name.

Go back to the terminal and run diskutil apfs list. Now you should get a list of your new volume — for your fast drive (disk0) it should say Main and for your slower disk it should say (aux).

Now install MacOS as usual.

If you’re using a non-Apple SSD after installing MacOS run - sudo forcetrim enable - in the terminal and restart.

Download BlackMagic Disk Speed Test from the App Store (Free) to test if you’re getting the expected speeds.
That worked for me, and I'm now getting NVMe speeds from the fusion drive. And my fans are running very quiet now, hovering around the 1200rpm minimum.

I do not think I would have chosen to take this on just to put in a small SSPOLARIS drive. That said, it's a step up in size from the 32 GB SSPHOTON my iMac shipped with, and probably a step up in speed as well; I didn't think to test the original drive while it was still in, but but I've seen a table that suggests the SSPHOTONs are slower. So my storage isn't much larger, but I'm hoping that between the bigger NVMe drive and swapping the HDD for an SSD, it will be snappier. I definitely wouldn't do this again. If I find I need more storage, I'll be adding it in the form of external drives.

For anyone reading this thread who's considering doing the upgrade, there's a lot of enthusiasm in the posts, so I'll be a contrary voice. This really is pretty difficult and stressful--not impossible by any means, but far from trivial. I had some really tense moments with delicate connectors. There's no guarantee your drive will actually work in a form you're happy with, and if you reassemble the computer after installation (even without reattaching the LCD), you'll have to have a clear couple of hours to tear things down each time you want to make a change. Things turned out okay for me, but if I had to make a decision about whether to do it again, knowing what it's like, I wouldn't.
 

sebastienc

macrumors newbie
Oct 14, 2019
12
0
*FINAL* UPDATE

Well, I can't explain why but my Temps are all normal now!!
970 EVO is in the 39-46C range (normal/mild load)
CPU/Logic Board under 40C (normal/mild load)
Haven't been conducting any stress tests though to see what happens under heavy load. The upgrade by itself raised my temperature enough, so I'm not looking forward to tinkering with a system that works! Haha.
So I'm going to let my iMac be. And I'm quite happy with the outcome.

Cheers
 

Hurban1983

macrumors newbie
Sep 10, 2019
5
0
Oslo
Hi! I have put a 970 EVO Plus in a 2017 iMac. Before installing I took it to a computer service store who could put the m2 in a windows-computer and upgraded the firmware for me. I paid like $20 for this, as I have no people around who could do it for me. I just have to trust that they made the proper firmware-upgrade. At any rate, this m2 cannot be detected after install, even when I have used Unetbootin and Etcher Could it be hardware-related? I cannot for the life of me figure out why this is happening! I have used equipment (like the recommended Sintech adapter (ST-NGFF2013C)) and procedures described in this comprehensive thread.

Any suggestions? I cannot see that most people here have trouble in detecting the m2?
 

sebastienc

macrumors newbie
Oct 14, 2019
12
0
Hi Urban, I'm not familiar with the 970 Plus and which firmware version you need. However, it's a pretty straightforward update to do, so I'm going to trust you have the right firmware.
Now, have you tried to reboot in Recovery mode (pressing the R key) from a USB MacOs boot drive? From there you should be able to go in the Disk Utility and format your new M2 drive, and install macOS on it.
 

Hurban1983

macrumors newbie
Sep 10, 2019
5
0
Oslo
Thanks Sebastienc, I will give it a try with the boot drive. I have tried to go by recovery mode with a time machine drive, but my machine could not detect the drive to install it... I will keep you posted!
 

Hurban1983

macrumors newbie
Sep 10, 2019
5
0
Oslo
Hi Urban, I'm not familiar with the 970 Plus and which firmware version you need. However, it's a pretty straightforward update to do, so I'm going to trust you have the right firmware.
Now, have you tried to reboot in Recovery mode (pressing the R key) from a USB MacOs boot drive? From there you should be able to go in the Disk Utility and format your new M2 drive, and install macOS on it.
[/QUOTE]

Still no luck with boot drive...
 

sebastienc

macrumors newbie
Oct 14, 2019
12
0
@Hurban. Have you applied Kapton? Checked that the drive is well seated in the adapter and the adapter not in contact with the shielding? Do you have an M2 to USB-C adapter so you could test the drive (either on another computer if your iMac is your only computer, or with the MacOS USB boot drive)?
 

Hurban1983

macrumors newbie
Sep 10, 2019
5
0
Oslo
Hi again, I have not used Kapton, but I have used electric tape. I have tried to adjust the m2 four times over. Still no luck. I will take out the m2 into a thunderbolt chassy as soon as it arives so I can test it. In the meantime, my screen is now showing blue and pink stripes after all the assemly, so I might have screwed up the screen in this agonizing process. Starting to regret ever starting it.
 

paulbee

macrumors member
Nov 17, 2011
65
4
In the meantime, my screen is now showing blue and pink stripes after all the assemly, so I might have screwed up the screen in this agonizing process. Starting to regret ever starting it.
Sounds like this could be a problem with the LCD display cable. If you haven't already, I'd try carefully disconnecting it and reseating it, and also inspecting both the cable end and the connection on the board for damage. I believe it's also possible to replace the display cable, so if you can't make progress otherwise that's something else to look into. Good luck!
 

Hurban1983

macrumors newbie
Sep 10, 2019
5
0
Oslo
Sounds like this could be a problem with the LCD display cable. If you haven't already, I'd try carefully disconnecting it and reseating it, and also inspecting both the cable end and the connection on the board for damage. I believe it's also possible to replace the display cable, so if you can't make progress otherwise that's something else to look into. Good luck!
Thanks paulbee. As I see it, it could be the screen (and perhaps the cable you suggests), or the graphics card. There are a number of videos of people with older macs on YT who have similar issues, where the graphics card is at fault. A straightforward way to check this is to connect an external monitor, and if the problem is on both screens it confirms its the graphics card that you need to fix. My reasoning now is to first do this test - If it is the graphics card, then I think you now have to replace the whole motherboard to fix it as it is soldered to the motherboard. I am curious, however, if I can bypass the whole issue with an external GPU. If that is possible, I don't mind it that much, where I can rather change the motherboard at a later stage. If it is the screen, however, I really hope that I can just exchange the cable as you suggests. Otherwise, replacing the whole screen is an expensive hassle.

In terms of the m2 issue, I am waiting for an external thunderbolt chassis. My plan is to install the OS on the SSD connected to the SATA, and see if it shows up. If it does, then the problem is one of two things: either the adapter is faulty, or I bought the used iMac where the fusion-drive was out of order from the beginning. I did not check this thorougly, but I would really advice everyone to check this before they start the procedure in this thread. I will of course try to reinstall the original 32GB blade to see if it shows up.

So, this is where I'm at. As the whole thing sort of went to hell, I guess the best ally is time and patience.
 

yurkennis

macrumors newbie
Dec 1, 2010
7
0
First, I'd like to thanks @rsx0 and everyone who made this thread so detailed and useful.

Three questions I failed to find answers for, possibly because I didn't read careful enough:

1) Is the write speed issue with 2TB 970 EVO Plus actually solved now? I've seen two contradicting points on this:
- @rxs0 reporting "very MEDIOCRE write speeds of 977 MB/Sec" (only mentioned in an June 19th update to #12), with later report in #28 that the speed issue (of 970 EVO non-plus?) was solved with switching to ST-NGFF2013C adapter
- @arnd13 reporting wonderful 2.9GB write/3.0GB read speeds with Plus in #85, but not mentioning how he achieved such results (and whether any difficultes issues were experienced on the way)

2) Are 32GB RAM modules possible with any build-in iMac 2017 27" processor, or only with i7 7700 processor, per #63? Specifically I'm considering to use them for 4-core 3.8 GHz Intel i5 (7600K) iMac (MNED2LL/A - A1419 - 3070), to have only 64GB for now but possibly to move those RAM sticks later to eg. iMac 2019.

3) Is it possible to complement the larger RAM modules to the iMac's pre-installed modules? If so, is it OK that the larger RAM will be 2666 GHz, which is faster than the original 2400GHz?
And should I buy a second module nearly-identical to the pre-installed module, eg if they work at full speed only if two modules work in parallel? If I should, how can I find out a manufacturer and model of the pre-installed RAM module? Found out that my iMac comes with 2x4GB, which answers the striked-through part of my question.​
 
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psymac

macrumors 6502a
Jul 17, 2002
523
125
First, I'd like to thanks @rsx0 and everyone who made this thread so detailed and useful.

Three questions I failed to find answers for, possibly because I didn't read careful enough:

1) Is the write speed issue with 2TB 970 EVO Plus actually solved now? I've seen two contradicting points on this:
- @rxs0 reporting "very MEDIOCRE write speeds of 977 MB/Sec" (only mentioned in an June 19th update to #12), with later report in #28 that the speed issue (of 970 EVO non-plus?) was solved with switching to ST-NGFF2013C adapter
- @arnd13 reporting wonderful 2.9GB write/3.0GB read speeds with Plus in #85, but not mentioning how he achieved such results (and whether any difficultes issues were experienced on the way)

2) Are 32GB RAM modules possible with any build-in iMac 2017 27" processor, or only with i7 7700 processor, per #63? Specifically I'm considering to use them for 4-core 3.8 GHz Intel i5 (7600K) iMac (MNED2LL/A - A1419 - 3070), to have only 64GB for now but possibly to move those RAM sticks later to eg. iMac 2019.

3) Is it possible to complement the larger RAM modules to the iMac's pre-installed modules? If so, is it OK that the larger RAM will be 2666 GHz, which is faster than the original 2400GHz?
And should I buy a second module nearly-identical to the pre-installed module, eg if they work at full speed only if two modules work in parallel? If I should, how can I find out a manufacturer and model of the pre-installed RAM module? Found out that my iMac comes with 2x4GB, which answers the striked-through part of my question.​
I've found that the Samsung Evo 970 does perform well for single writes on my 2017 iMac 27", while sequential writes slow down (reads not affected) very quickly due to Samsung's temp throttling. Blackmagic Speed Test is for sequential R/W, while AJA System Test Lite can be configured for both single (default) and sequential R/W. I've read the 970 EVO plus performs better for sustained R/W, as of course Apple's (Samsung) SSPOLARIS OEM SSDs. Tempted to swap out my Evo for the Evo plus, but not sure if worth it, pleased so far with the performance.
 
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QurazyQuisp

macrumors newbie
Nov 3, 2006
28
2
Jersey City, NJ
So, I opened my mid-2017 up to add a new nvme ssd and put new thermal paste on the 7600k.

I did all the work, got a single led and it seemed to begin booting up and then nothing. No diagnostic lights, nothing. I’ve now tried 3 power supplies, I believe they’re fine (multimeter shows power in the right places). But I still have no diagnostic lights (I’ve confirmed everything is plugged in).

Did I somehow fry the logic board ??
 

madoleo

macrumors newbie
Oct 6, 2019
5
2
I would remove cpu heatsink and try position it once again, I think I have seen similar story on another thread.
 
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JonathanJK

macrumors newbie
Nov 28, 2019
1
0
Hey there I’ve been reading this forum discussion for a few weeks now to check and double check everything as I’m about to take the plunge and I have a few questions. Before I share the questions I do have to say I’m impressed with the work expressed here, thank you, I used to be a member of the forums way back in the the 00’s and deleted my account. This topic has provoked me in creating a new username to join back in. Thank you again. I bought my iMac 2017 a few months back and now I'm ready to open it up.

Some questions first:

1. On the very first page you list item component 30. What is this for exactly? I’m under the impression this cable is for the realists among us who want to test the iMac before sticking it fully back together again?

2. Quinn Nelson did an upgrade similar to this and he also mentions a cable that is over priced and has to be bought on ebay (regarding data transfers).


He doesn’t list this in his video of items to buy, nor does he list the long Sintech adapter you recommend (later realising he didn't upgrader the blade SSD [see Q3a]). I nearly purchased everything I thought I needed until I double checked this thread.

2a. Quinn only replaces the SATA HDD with the SATA SSD, does this mean he keeps his Fusion Drive? The OG Apple SSD + the Crucial MX drive he uses or does it revert to 2 drives? I’m unsure of how the system sees both drives now.

2b. What is the advantage to just upgrading the SATA drive instead of the PCIe drive? Performance benkmarks seem to be a big deal for him, but he didn’t opt for the PCIe upgrade.

3. Am I right in thinking, if I just back everything up and pull out the drives, swap in the 970 Evo and boot up, the system will ask to reinstall itself from the internet with option + R? I’m running Catalina at the moment, so does that do anything to the firmware so I don’t install the original OS?

With that I’m referring to point 12 on the MacOS Operating System Installation on New Drives and Recommended Supportive Hardware list. My simple brain sees a chicken and the egg problem unless the firmware is aware prior to installing the new drives and before the new OS.

5. I’m not too sure about the firmware updating malarky that’s going on, can I assume I don’t have to use the software you’re suggesting, by now SamSung will have patched the newest drives off the production line right? I only have a spare Macbook Pro lying around and I noticed comments from others who are updating their blade SSD’s via windows machines.

Okay thanks for enabling this, I hope these questions also fill in the gaps for others who may be lurking.

My "To Purchase" list (because of this thread):
CRUCIAL MX500 2TB 1780 (maybe need)
OWC in-Line Digital Thermal Sensor HDD Upgrade Cable (maybe need)
Samsung 1TB 970 EVO

My "Purchased" list:
i7 7700k (rare in Hong Kong [where I live], so I snagged a second hand one asap just today in fact, might be a while before I get another).
Alcohol (for cleaning)
NewerTech AdaptaDrive 2.5" to 3.5" Drive Converter Bracket
Odyson - VHB LCD Display Adhesive Strips Replacement for iMac 27" A1419 (Late 2012-Mid 2017)
Thermal Paste
screwdriver set
EKWB EK-M.2 NVMe Heatsink
Kapton Tape, 1/4"
Sintech NGFF M.2 nVME SSD Adapter Card

EDIT: Tagging @rxs0 to get some feedback. Thanks.
 
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rustyhalo93

macrumors newbie
Nov 2, 2016
4
2
FINAL UPDATE:
...
Drum roll...
...
I got the sucker to work!

Short update: Metal spring underneath the CPU is the prb. You have to unbend it.

Longer answer:
1. When I pulled the CPU out I saw one corner slightly bent. The mutli-layer PCB is soft, so it's possible to straighten it. It also meant that something was bending it.
Almost all the thermal paste was also squished to the sides. So there was way too much pressure on the CPU.
This also meant that some of the PINs in the corner were not connecting. Thus the Logic board wouldn't boot.
Getting LED 1 or LED 1-2 both means CPU issue. Ultra fan speed also was due to that...

2. I've removed quite a bit of tension from the spring. I spent so many hours in the last few days on that "upgrade", that I got tried and didn't take a picture of the prior. But here is the after:
View attachment 870444

3. After that not all was smooth, but I got it to boot and I couldn't wait to seal the damn thing. So I just did that... Before realizing that I had forgotten to screw the speakers! Haha.
Well I took out the logic board 4 times. Tested the i7-700K twice. Put the i5-7600 back in. Then installed/uninstalled/reinstalled the i7-7700. So I was ready before seeing it worked to remove the board again, and thus left the speakers loose.

Results:
Great speeds with the NVME and SSD, and I got an 8 threads CPU.
View attachment 870447 View attachment 870448

Next steps: Happy to help anyone here with questions. However, I'm not trouble free.
The Samsung EVO 970 run ultra hot!! 75C under mild load. The heatsink touches the housing which I hope will help dissipate some heat, but It's a bit of a worry.

Good luck to anyone still working on their rig!
Hi sebastienc,

Thank you for your detailed recording of your own adventure, your post really really helped me on my Late 2015 iMac 27 NVME SSD and CPU upgrade, the last two days was an ordeal for me, and I am so happy to be able to pull it off and write to you on my upgraded iMac!

So you are very accurate on the diagnostic LED behavior, I also experienced two type of diagnostic LED behavior: 1. only LED 1 is on when plugged in, no response when power button is pressed, diagnostic port on motherboard didn't read 12V input from terminal 1 (GND) and terminal 11 (power on signal).
2. LED 1 and 2 went on when plugged in even without power button press, then LED 2 went off for a brief second, went on again and the fan starts to spinning like crazy.

These, like you said, are all related to CPU not properly seated, and that metal bracket really is making everything 10x more difficult. The tension is too high and we risk bending CPU PCB. Also, when applying screws on the metal brakes, the cooler may be lifted up a bit, taking CPU with it cause of the thermal paste, and then if we keep applying the pressure, we will risk bending the pin on the motherboard.

Thank you again for your post.
 

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Php4u

macrumors newbie
Oct 9, 2018
2
0
Sacramento, CA
So, I opened my mid-2017 up to add a new nvme ssd and put new thermal paste on the 7600k.

I did all the work, got a single led and it seemed to begin booting up and then nothing. No diagnostic lights, nothing. I’ve now tried 3 power supplies, I believe they’re fine (multimeter shows power in the right places). But I still have no diagnostic lights (I’ve confirmed everything is plugged in).

Did I somehow fry the logic board ??
I have a similar situation. I just upgraded my mid-2017 27: iMac with an SSD, NVMe and 7700 CPU. Now I get a black screen. When I look at the MOBO, I see 2 green lights (out of 5) that are green. A few differing posts show that to be a GPU issue. Never had it before? One suggestion was to reseat the onboard battery, which I will do now.

Any other suggestions? Very puzzled.
 

rustyhalo93

macrumors newbie
Nov 2, 2016
4
2
I have a similar situation. I just upgraded my mid-2017 27: iMac with an SSD, NVMe and 7700 CPU. Now I get a black screen. When I look at the MOBO, I see 2 green lights (out of 5) that are green. A few differing posts show that to be a GPU issue. Never had it before? One suggestion was to reseat the onboard battery, which I will do now.

Any other suggestions? Very puzzled.
Hi Php4u,

Did the LED2 came up without pressing the power button? You may want to check CPU, this may indicates your CPU is not properly seated.

Best
 

waffffffle

macrumors newbie
Jul 31, 2010
4
2
Thanks to all the great information from rsx0 in this thread, I just completed surgery on my iMac 5K (2015). Starting with a 3.1 TB Fusion Drive, I installed both an Intel 660p 2TB NVME blade using the Sintech adapter as well as a 4TB WD Blue SATA SSD in the hard drive bay. I now have a 6TB all SSD Fusion Drive. In the future I’m considering adding a second 4TB SSD using one of those dual 2.5-to-3.5 RAID adapters But 6TB should suffice for a while.

The installation went successfully with the exception of the glue tape strips. I will need to order a new set and do that part again. Those issues are mostly due to human error (I somehow managed to close the iMac up twice without connecting the display cables, it was a long day).

A few notes that may be useful to others:

The whole process took about 4 hours, although I had about a 30 minute break in the middle to take a phone call where I did less work. Aside from the issues with the display tape the rest was pretty straightforward and I feel confident I could easily do it again.

The Sintech adapter fit very well using the original screw that held in the original SSD blade. I am completely confident that it won’t budge. I did not use a heat sync or any tape on the SSD.

The painters tape trick for keeping track of screws worked great. Definitely recommend that to others.

I bought an iMac service wedge but found that it wasn’t helpful.

Checking that everything is working before sealing up the iMac was my personal downfall since I forgot to reconnect the cables when sealing up the iMac (twice). I wasted two sets of tape adhesive and will need to order more. It’s currently held together with the second set so the seal isn’t great. I have the iMac display edges wrapped up in painters tape for now as I’m uneasy about the seal with the OWC tape after I had to open it again. I’m going on vacation for a couple of weeks so I won’t be able to fix the adhesive for a while. I think I might leave my iMac face down on a table during that time just in case.

Getting the glass back on perfectly straight is pretty tricky. Are there any tools or tricks to make sure it sits just right? At first I had difficulty getting the bottom to sit close enough while the iMac was lying down. It was also hard to get the sides to line up just right.

I purchased the OWC kit with the thermal sensor from Amazon. The kit does not include a spudger, but it clearly needs one (I bought that separately thanks to the info in this thread). It also doesn't include a T20 bit needed to take the the motherboard out, which is understandable since that’s not needed for just a SATA install, however that was pretty much the only reason I needed the entire separate toolkit. That and the need for a longer T8/10 to reach the recessed (captured) screw to get the motherboard off.

The adhesive tape I purchased from eBay is clearly thicker and puffier than the tape from OWC. Neither tape fit perfectly but I would definitely avoid the OWC tape given its thickness.

I used these 2 OWC youtube videos as a reference, but they wren’t 100% accurate:

In many case the video would claim a screw was a T8 or T10 when it was the opposite.

There were 7 screws needed to remove the motherboard, not 6.

The wireless attenna cables were held together with a couple of screws as well. That wasn’t shown in the video and made things a little tricker. Their trick of holding the antenna cables together with scotch tape didn’t work out as well for me as I think a couple of them moved due to the extra screws that I mentioned.


Right now I’m waiting for Migration Assistant to finish from my old drive but initial benchmarks are promising.
 
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DunDrent

macrumors newbie
Jan 20, 2020
3
2
hi rxs0 Thank you very much for your work and experience.

I have iMac (Retina 5K, 27-inch, Late 2015)

I bought: M2 SSD SAMSUNG 970 EVO Plus M.2
It is written on the production date 2019. 06 Maybe it already has a new firmware?

I have not bought an adapter yet. I'm at a loss and have already begun to desire that I did not buy a simple SAMSUNG 860 EVO SSD 2.5.

Should I start disassembling, I have no experience.
I am doing the same in my 2017 Imac.
Now buying an adapter so I can update the firmware.
I have installed it as is but is using only 2 lanes instead of 4.

DunDrent
 

DunDrent

macrumors newbie
Jan 20, 2020
3
2
Hi Php4u,

Did the LED2 came up without pressing the power button? You may want to check CPU, this may indicates your CPU is not properly seated.

Best
Yes, I have had the same a few times.
Also could be memory.
Make sure the memory is the same as tested prior the change, including exactly the same blade in each slot.

DunDrent
 
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