2017, 27-inch Retina 5K iMac - 128GB Ram Upgrade

rxs0

macrumors member
Original poster
Apr 4, 2019
52
67
I have successfully upgraded my 2017, 27-inch Retina 5K iMac with 128GB of Samsung DD4 2666MHz SODIMM ram.

(4) Samsung 32GB DDR4 2666MHz sodimm of ram (M471A4G43MB1-CTD)

Model Name: iMac
Model Identifier: iMac18,3
Processor Name: Intel Core i7
Processor Speed: 3.6 GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256 KB
L3 Cache: 8 MB
Memory: 128 GB

New as of May 13, 2019:
Boot ROM Version: 172.0.0.0.0

SMC Version (system): 2.41f1

Old:
Boot ROM Version: 170.0.0.0.0

SMC Version (system): 2.41f1

No problems with hardware and recent software macOS Mojave upgrade (5-13-19), Version 10.14.5. This update is primarily for AirPlay 2 support.

https://www.macworld.com/article/3394579/apple-releases-macos-10-14-5-mojave.html
https://support.apple.com/en-us/HT209149#macos10145

The system is running really stable. No instability events or crashes.

See prior post for benchmarks - https://forums.macrumors.com/threads/imac-retina-5k-27-inch-2017-cpu-and-nvme-ssd-upgrade-pitfalls-and-tips.2177812/page-3#post-27358749

I'd rather buy the 2666MHz ram instead of the 2400MHz ram in case I upgrade to the 2019 27-inch iMac.

https://www.samsung.com/semiconductor/insights/news-events/the-industrys-first-32gb-ddr4-sodimm/
https://www.samsung.com/semiconductor/dram/module/M471A4G43MB1-CTD/
https://www.samsung.com/semiconductor/global.semi/file/resource/2018/07/M471A4G43MB1-CTD00.pdf

Samsung 32GB DDR4 2666MHz RAM Memory Module for Laptop Computers (260 Pin SODIMM, 1.2V) M471A4G43MB1
https://www.amazon.com/gp/product/B07N124XDS/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

Thanks
 

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tdgrn

macrumors 6502
May 1, 2008
357
7
Little Rock, AR
I have successfully upgraded my 2017, 27-inch Retina 5K iMac with 128GB of Samsung DD4 2666MHz SODIMM ram.

(4) Samsung 32GB DDR4 2666MHz sodimm of ram (M471A4G43MB1-CTD)

Model Name: iMac
Model Identifier: iMac18,3
Processor Name: Intel Core i7
Processor Speed: 3.6 GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256 KB
L3 Cache: 8 MB
Memory: 128 GB

New as of May 13, 2019:
Boot ROM Version: 172.0.0.0.0

SMC Version (system): 2.41f1

Old:
Boot ROM Version: 170.0.0.0.0

SMC Version (system): 2.41f1

No problems with hardware and recent software macOS Mojave upgrade (5-13-19), Version 10.14.5. This update is primarily for AirPlay 2 support.

https://www.macworld.com/article/3394579/apple-releases-macos-10-14-5-mojave.html
https://support.apple.com/en-us/HT209149#macos10145

The system is running really stable. No instability events or crashes.

See prior post for benchmarks - https://forums.macrumors.com/threads/imac-retina-5k-27-inch-2017-cpu-and-nvme-ssd-upgrade-pitfalls-and-tips.2177812/page-3#post-27358749

I'd rather buy the 2666MHz ram instead of the 2400MHz ram in case I upgrade to the 2019 27-inch iMac.

https://www.samsung.com/semiconductor/insights/news-events/the-industrys-first-32gb-ddr4-sodimm/
https://www.samsung.com/semiconductor/dram/module/M471A4G43MB1-CTD/
https://www.samsung.com/semiconductor/global.semi/file/resource/2018/07/M471A4G43MB1-CTD00.pdf

Samsung 32GB DDR4 2666MHz RAM Memory Module for Laptop Computers (260 Pin SODIMM, 1.2V) M471A4G43MB1
https://www.amazon.com/gp/product/B07N124XDS/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

Thanks

Thank you for sharing. This interests me because of my home lab use for professional development.
 
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Kevbasscat

macrumors regular
Oct 10, 2016
209
142
Banning, CA 92220
Can this be done on a mid 2017 5k, i5, 3.8GHz, Radeon Pro 580, 32Gb DDr4 2400MHz? Does the same firmware update apply? Is that what allows this installation or is it the CPU?
 

Zdigital2015

macrumors 68000
Jul 14, 2015
1,689
1,738
East Coast, United States
Can this be done on a mid 2017 5k, i5, 3.8GHz, Radeon Pro 580, 32Gb DDr4 2400MHz? Does the same firmware update apply? Is that what allows this installation or is it the CPU?
It should work just fine, although 128GB is not officially supported by Intel for the OP’s Core i7-7700 (3.6GHz) or your Core i7-7600K, although there were rumblings that Intel was going to correct that and officially support that amount of DRAM on 7th Gen (saw it on AnandTech, but cannot find the article), they only seem to have updated support on the 8th Gen Core i5 and above.

Your iMac should be running BootROM 172.0.0.0 if you have upgraded to Mojave 10.14.5.

The only caveat is that Apple has been known (not lately) to change things with regard to DRAM/Memory between firmware updates that screw things up - https://beetstech.com/blog/memtest86-bug-discovery-and-workaround

I have not noticed anything in the past couple of years with regard to Apple tightening up DRAM timings, et al. But buyer beware should you go this route.
 
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Kevbasscat

macrumors regular
Oct 10, 2016
209
142
Banning, CA 92220
It should work just fine, although 128GB is not officially supported by Intel for the OP’s Core i7-7700 (3.6GHz) or your Core i7-7600K, although there were rumblings that Intel was going to correct that and officially support that amount of DRAM on 7th Gen (saw it on AnandTech, but cannot find the article), they only seem to have updated support on the 8th Gen Core i5 and above.

Your iMac should be running BootROM 172.0.0.0 if you have upgraded to Mojave 10.14.5.

The only caveat is that Apple has been known (not lately) to change things with regard to DRAM/Memory between firmware updates that screw things up - https://beetstech.com/blog/memtest86-bug-discovery-and-workaround

I have not noticed anything in the past couple of years with regard to Apple tightening up DRAM timings, et al. But buyer beware should you go this route.
Thank you so much. Very helpful and informative, advice, and the article was an eye opener. That is a wonderful site with tons of good advice. You're correct, I am on BootROM 172.0.0.0 with 10.14.5. I was pi***ed when Apple blacklisted my 9,1 iMac because it wouldn't take Mojave, so I came here and after learning and venting a bit lol, decided Apple was just moving forward in tech and I shouldn't be such whiner, lol. So I. bought a new iMac, and imagine my surprise...when it didn't come with Mojave on it. So I got on the phone after ripping some agent a new one and they walked me thru the update right then and there.
Nice, but I'm curious. What do you need 128 GB for?
Haha, why do guys put headers and rebuild their perfectly good cars so they can go to some remote spot every blue moon and spin the tires and get that adrenaline rush? Or go climb El Capitan? If it's not for some crazy video edits, or insane math compiles, it's most likely a testosterone thing. I'm still guilty of it even at 64 yo. More is better, you know:). Someday I'll grow up, but I hope it isn't any time soon. Denial is still a river in Egypt isn't it? Lol.
 
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itsjustdibella

macrumors newbie
Sep 9, 2018
8
2
Rochester, NY
I have successfully upgraded my 2017, 27-inch Retina 5K iMac with 128GB of Samsung DD4 2666MHz SODIMM ram.

(4) Samsung 32GB DDR4 2666MHz sodimm of ram (M471A4G43MB1-CTD)

Model Name: iMac
Model Identifier: iMac18,3
Processor Name: Intel Core i7
Processor Speed: 3.6 GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256 KB
L3 Cache: 8 MB
Memory: 128 GB

New as of May 13, 2019:
Boot ROM Version: 172.0.0.0.0

SMC Version (system): 2.41f1

Old:
Boot ROM Version: 170.0.0.0.0

SMC Version (system): 2.41f1

No problems with hardware and recent software macOS Mojave upgrade (5-13-19), Version 10.14.5. This update is primarily for AirPlay 2 support.

https://www.macworld.com/article/3394579/apple-releases-macos-10-14-5-mojave.html
https://support.apple.com/en-us/HT209149#macos10145

The system is running really stable. No instability events or crashes.

See prior post for benchmarks - https://forums.macrumors.com/threads/imac-retina-5k-27-inch-2017-cpu-and-nvme-ssd-upgrade-pitfalls-and-tips.2177812/page-3#post-27358749

I'd rather buy the 2666MHz ram instead of the 2400MHz ram in case I upgrade to the 2019 27-inch iMac.

https://www.samsung.com/semiconductor/insights/news-events/the-industrys-first-32gb-ddr4-sodimm/
https://www.samsung.com/semiconductor/dram/module/M471A4G43MB1-CTD/
https://www.samsung.com/semiconductor/global.semi/file/resource/2018/07/M471A4G43MB1-CTD00.pdf

Samsung 32GB DDR4 2666MHz RAM Memory Module for Laptop Computers (260 Pin SODIMM, 1.2V) M471A4G43MB1
https://www.amazon.com/gp/product/B07N124XDS/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

Thanks
How are you able to put 128gb RAM in that 2017 5K iMac I thought the MAX MAX was 64gb?? What am I missing? Is it due to boot rom upgrade or something? I just ordered 32gb RAM to start off and will add another 32gb during NVMe ssd and SATA ssd install....can I really put 128gb RAM?
 

RyanXM

macrumors 6502
Jul 7, 2012
329
351
DFW, TX
How are you able to put 128gb RAM in that 2017 5K iMac I thought the MAX MAX was 64gb?? What am I missing? Is it due to boot rom upgrade or something? I just ordered 32gb RAM to start off and will add another 32gb during NVMe ssd and SATA ssd install....can I really put 128gb RAM?
128GB works in the 2017 as long as you have updated to at least 10.14.5. There was a firmware update that happened that then allowed 128GB. We have tested it here and it works well!
 

itsjustdibella

macrumors newbie
Sep 9, 2018
8
2
Rochester, NY
How are you able to put 128gb RAM in that 2017 5K iMac I thought the MAX MAX was 64gb?? What am I missing? Is it due to boot rom upgrade or something? I just ordered 32gb RAM to start off and will add another 32gb during NVMe ssd and SATA ssd install....can I really put 128gb RAM?
Welp looks like I should return the 32gb and get something good for mean time lol thanks a ton!
 

BoostMyRig

macrumors newbie
Oct 11, 2019
9
1
I have a 2017 5k 27inch i7 4.2 with on board 1T SSD 64GB RAM.

Has anyone tested 128GB to confirm it uses 128GB RAM? Intel Kaby Lake z270 board only can use 64GB max.

I ordered 4 of the Samsung 32s referenced here (not installed yet) but would hate to open them only to find out on paper the OS see's the extra RAM but technically cannot use it.

I would like to hear from anyone that has done this 128GB RAM upgrade to your 2017 5k 27inch i7 and it not only shows it installed but actually works and uses all 128GB RAM using software test.

OWC shows on YouTube 2019 model working with a 128GB upgrade. They made sure to confirm all of it can be used with Atom software test. No doubt iMac can see and report a total of 128GB RAM but does it really use it is what I am trying to confirm.

Thanks
 

BoostMyRig

macrumors newbie
Oct 11, 2019
9
1
128GB works in the 2017 as long as you have updated to at least 10.14.5. There was a firmware update that happened that then allowed 128GB. We have tested it here and it works well!
That sounds great! Did you test it in similar fashion to how OWC tested the 2019 iMac with 128 GB In their YouTube video?
From what I saw in their video it is easy to be tricked into thinking that the system is actually using all of the 128 GB when in fact it may only be using 64 GB. They showed how to check for that to make sure that all 128 GB is in fact being used and not just being seen by the OS.

I ask because I have ordered 128 GB of the Samsung 32GB sticks as referenced in this forum and rather not open it and install it if in fact it does not work.

Thank you guys. Would Like to hear feedback to confirm.
 

RyanXM

macrumors 6502
Jul 7, 2012
329
351
DFW, TX
That sounds great! Did you test it in similar fashion to how OWC tested the 2019 iMac with 128 GB In their YouTube video?
From what I saw in their video it is easy to be tricked into thinking that the system is actually using all of the 128 GB when in fact it may only be using 64 GB. They showed how to check for that to make sure that all 128 GB is in fact being used and not just being seen by the OS.

I ask because I have ordered 128 GB of the Samsung 32GB sticks as referenced in this forum and rather not open it and install it if in fact it does not work.

Thank you guys. Would Like to hear feedback to confirm.
I used the machine for over two months as my daily driver. It used all 128GB.
 
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BoostMyRig

macrumors newbie
Oct 11, 2019
9
1
Anyone else confirm this?

I have the i7-7700k which says via intel direct 64GB supported max. So I am a bit cautious that all 128GB is being used.

I would like to see an actual screen shot of someone using i7-7700k iMac with 128GB showing it all being used via testing software similar to what was done with OWC on the 2019 iMac that truly supports 128GB.

If the i7-7700k board supports 128GB it seems strange that OWC is not selling or promoting 128GB for any iMac i7-7700k.
 

RyanXM

macrumors 6502
Jul 7, 2012
329
351
DFW, TX
@BoostMyRig Do you not have the 4x32GB of RAM in hand already? Any reason you aren't opening them and installing them? No return if opened? They will work 100%. We've tested them to no end and the machine runs without issue.

I ordered 4 of the Samsung 32s referenced here (not installed yet) but would hate to open them only to find out on paper the OS see's the extra RAM but technically cannot use it.
 

BoostMyRig

macrumors newbie
Oct 11, 2019
9
1
Should receive them today or tmrw. I can return them no problem but I prefer not to waste time installing them if in fact they just won't work as hoped. I appreciate the help and repy regarding this install but I am generally pretty thorough in my approach when it comes to upgrading electronics of any kind. Too many times there are caveats attached to certain upgrades. I don't want this one to be one of those with caveats if it can be avoided.

Thank you for your generous input.
 
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Zdigital2015

macrumors 68000
Jul 14, 2015
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East Coast, United States
Should receive them today or tmrw. I can return them no problem but I prefer not to waste time installing them if in fact they just won't work as hoped. I appreciate the help and repy regarding this install but I am generally pretty thorough in my approach when it comes to upgrading electronics of any kind. Too many times there are caveats attached to certain upgrades. I don't want this one to be one of those with caveats if it can be avoided.

Thank you for your generous input.
I am still looking for the source to cite, but I swear I read an article about Kaby Lake being able to address 128GB of DRAM, although Intel would not likely issue any sort of update or formal support for it in the ARK due to its age. Intel did however go back and change the ARK listings for 8th Gen CPUs to give them “officially” supported support for 128GB of DRAM. Here is an informative article about 9th Gen receiving 128GB support. If I find the other article, which I believe I saw on Anandtech, I will edit this post. Good luck!

 
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BoostMyRig

macrumors newbie
Oct 11, 2019
9
1
I received the 128GB RAM today, installed and the Mac can see the 128GB RAM but cannot use it just as I suspected. Both Bootcamp (Win10) and the very latest Catalina update today does not allow more than 64GB to be used on this 2017 5k 27inch i7-7700k 4.2 turbo 4.5 Mac.

If you are wanting/thinking of doing this upgrade do not waste your time, effort or money (if not returnable). If someone says it does they are wrong. OWC did a 128GB install on a 2019 Mac and showed proof that not only did that Mac see but also could use the full 128GB installed. The Wired Memory info in Activity Monitor is the proof along with Atomic software RAM test.

My wired memory is 67.78GB. That is all the proof you need to see that your Mac cannot use all the Physical Memory installed. In my case 128GB. I can only use 64GB RAM not the Physical of 128GB which was installed. I knew going in that Kaby Lake i7-7700k shows only 64GB supported but others in this forum said it can use 128GB because it worked for them. There is no possible way it did work unless I'm missing something which is unlikely.

I would love for these to work, that is why I bought them but for others to say they tested extensively and works 100% is not true. I welcome anyone to show proof of this particular Mac to actually work with 128GB and not just show it can hold 128 GB. Like I said, I would keep them if in fact they worked but sadly they do not and are being returned.

Most likely I hear crickets when it comes to anyone showing proof they work. That is why OWC doesn't sell 128GB RAM upgrade for this model. If it could work they definitely would be selling it. I knew this going in but was willing to try installing them since others have said it worked 100% and they tested extensively. I hope I'm wrong but unlikely at this point.

See pics below.

Win10-RAMpic.PNG
Screen Shot 2019-10-15 at 4.30.19 PM.png
 
Last edited:

JacobHarvey

macrumors member
Apr 2, 2019
43
22
Somewhere
Thanks for digging a bit deeper and providing hard evidence on this matter. Do you also have the screenshot for the Atomic RAM test as well?

This reminds of when a reddit user posted that the iPhone 7 Plus supported USB 3 over lightning leading to a massive comment thread where everybody went mad over this 'great improvement'. Turns out that all iPhones to this day still only support USB 2.0 data speeds over lightning (as they only have 8 pins).

Nobody ever properly dug deeper and the original post was never corrected (I stumbled upon that reddit thread not long ago when googling the topic):

https://www.reddit.com/r/apple/comments/531uja
 
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BoostMyRig

macrumors newbie
Oct 11, 2019
9
1
Thanks for digging a bit deeper and providing hard evidence on this matter. Do you also have the screenshot for the Atomic RAM test as well?

This reminds of when a reddit user posted that the iPhone 7 Plus supported USB 3 over lightning leading to a massive comment thread where everybody went mad over this 'great improvement'. Turns out that all iPhones to this day still only support USB 2.0 data speeds over lightning.

Nobody ever properly dug deeper and the original post was never corrected (I stumbled upon that reddit thread not long ago when googling the topic):

https://www.reddit.com/r/apple/comments/531uja
No unfortunately I didn't but that was the last test I did and it showed Physical 128GB RAM but was only capable of using roughly 58 GB RAM considering overhead. So the Atomic test confirmed its just not possible to make use of 128GB RAM on the i7-7700k iMac.

I'm pretty thorough in my research before I attempt to try something like this but there is always that chance somebody knows something I don't. That is why I was willing to try this. Sadly, in this case, it won't work. I really wanted the 128GB to work but it just doesn't.
 

Zdigital2015

macrumors 68000
Jul 14, 2015
1,689
1,738
East Coast, United States
No unfortunately I didn't but that was the last test I did and it showed Physical 128GB RAM but was only capable of using roughly 58 GB RAM considering overhead. So the Atomic test confirmed its just not possible to make use of 128GB RAM on the i7-7700k iMac.

I'm pretty thorough in my research before I attempt to try something like this but there is always that chance somebody knows something I don't. That is why I was willing to try this. Sadly, in this case, it won't work. I really wanted the 128GB to work but it just doesn't.
Just out of curiosity, we’re you running Mojave or Catalina on your iMac?