Adamanta64GB (4x16GB) Memory Upgrade Compatible for 2017 Apple iMac 27" Retina 5K Display DDR4 2400MHz PC4-19200 SODIMM 2Rx8 CL17 1.2v Dual Rank RAM DRAM

EDIT: I just benchmarked the differences between my original 8GB VS New 32GB VS 40GB Combined. Running the iMac on just the new 32GB Adamanta RAM got the best results. (Photo of results provided) I did test on Geekbench and Novabench and the results were the same. 7-8% overall performance improvement compared to having the 40GB and even better than having the original 8GB. Where I noticed the most difference was in the responsiveness of the programs, cpu performance and also in the read and write speeds on the Fusion Drive. Huge memory performance boost by using the full utilization of the dual channel memory as opposed to dual channel asymmetric (which is technically single channel apparently) when you mix the modules. The best scenario would be to go for the full 64GB of this memory. I'm very pleased with 32GB however and not at all sweating missing out on the extra 8GB. I'll just sell them.Original Post:I had a similar problem as others with the iMac not starting up after installing the new ram in the empty slots. I first inserted this memory kit into the two empty slots on a new 2017 iMac i5 3.8ghz. The iMac wouldn't power on. I tried switching out the new modules in place of the original ones and putting the original memory into the empty slots. It wouldn't turn on. I then read someone else's post about putting the new modules in the TOP TWO slots (slots 1 and 2) and the old ones on the lower two slots (slots 3 & 4). IT WORKED and it does register as 40GB of ram. I haven't tested to see if there's an effect on performance. I read on Apple's website that you can have mixed ram and it maintains it's dual channel properties. Also, you want the largest RAM modules in the first bank (slots 1 and 2, the top two slots). Also your "iMac performs a memory initialization procedure when you first turn it on after upgrading memory or rearranging DIMMs. This process can take 30 seconds or more, and the display of your iMac remains dark until it's finished. Make sure to let the memory initialization complete." I called Adamanta to confirm the proper arrangement of these memory modules and they confirmed to place the new ram in the first/top two slots.

No current problems with ram. Easy install, cus it’s basic ram. Fast delivery. Will update if problems occur.

The listing said this would work in my 2017 iMac, and it did. Took less than 5 minutes to install, and now my Mac is no longer running low on memory with literally dozens of very complex windows open. I gave Tech Support a high rating because they anticipated the information I would need, and pointed me to the right place to show how to upgrade the memory on my Mac. I did not need to call or write to them, so I have no idea how they would respond. I would buy this product again, in a heartbeat!

this memory installed easy and worked great!!!! 5 stars

We purchased a 2017 Apple iMac, 27" Retina 5K display and wanted to immediately upgrade our RAM. After much research we decided on the Admanta (2X16GB) RAM cards. They were easy to install, using the included instructions and also confirming from available Apple tech docs. The upgrade took me about 10 minutes and our iMac booted up correctly the first time. Not one issue experienced after 6 months of use. A Quality product that performs as advertised and at a good price. I would buy and use this product again.

Easy to install in open slots. The only issue was the existing RAM in the #4 slot (bottom) did not seat completely when retainer locked. I had to push a little bit on the RAM after setting the retainer to seat it completely. If I did not do this, the iMac won’t boot when plugged back in and restarted. Not the RAM’s fault. Works great once installed and seated properly.

Removed the original 4 GB modules and installed the new 16 GB modules in the just vacated slots, then installed the original 4 GB modules in the remaining 2 slots, as recommended by several reviewers. The computer booted up immediately and showed 40 gb of memory. I had run Novabench before the upgrade and did it afterwards. The memory access increased from 11625 to 12261 MB/s and the FPO increased several percent. Other performance factors were unchanged. So much for decreased memory speed noted by others or trouble booting. I suspect it is the location of the new memory (i.e. in the same slots as the original modules) which eliminated the problem.Cannot be happier.

I have a 2017 27" iMac 5K with 8Gb RAM. I tried 32Gb of both Crucial and Hyper X but my Mac would never even boot, just black screen. Other people are using those brands with great results so I was beginning to think something was wrong with my new computer. I decided to try out Adamanta without much hope but lo and behold, my Mac booted right up! But... it was still reporting a measly factory 8Gb. Big sigh of disappointment thinking I'd have to return a third set of RAM. Before giving up hope, I just restarted my computer and woohoo! There was all 40Gb! Since then, everything has been flawless and fast.

Sin ningún problema después de tres años de estarlo utilizando.

iMac Retina 5K、27インチ、2017年、Big Sur OSの後にクラッシュし、オリジナルのDIMMを取り出して、スロットにこれを入れて、全く問題なし。問題は解決したようです。 少し驚きましたが、嬉しいです。