OWC 16GB (2 x 8GB) PC14900 DDR3 1866MHz SO-DIMMs Memory RAM Upgrade Compatible with 2015 (Late) iMac 27 w/Retina 5K Models and Compatible PCs (OWC1867DDR3S16P)

Worked perfectly in my iMac (late 2015). No compatibility issues. Easy to install and great memory quality. No issues with freezing or lag. My mac is running like new again!

I had a late 2015 27in Mac with 16gb in it. After discussion and research with apple and others, I decided to upgrade all 4 8gb sticks instead of just adding 2, I now have 32gb. I cant tell you how much better my machine runs, everything I do from programs to internet. I have fallen in love again, lol. We all love speed. This is a respected brand, was super easy to install and worked instantly. Apple charges $200 for 8 gb, I got 32 for $80.

Note, there are configuration changes needed to install this memory on that NAS model (look online).The memory has worked consistently without issues for over a month of continuous usage.UPDATE:The Synology device started crashing or failing to boot altogether.Nothing inherently wrong with the memory itself, it's just not really compatible with this NAS model.

I recently upgraded my 27-inch iMac (Late 2015 model) with the OWC 32GB (4 x 8GB) PC14900 DDR3 1866MHz SO-DIMMs, and I couldn’t be happier with the results.The installation was a breeze. Even for someone who doesn’t tinker with hardware often, the process was straightforward, thanks to OWC’s design and compatibility. Within minutes, I had all four sticks installed, and my iMac recognized the full 32GB of RAM without a hitch.The difference in performance is night and day. My machine, which was beginning to show its age, now feels incredibly snappy and responsive. Multitasking is effortless, with no lag even when running resource-intensive applications like Photoshop or Final Cut Pro. It’s like breathing new life into my iMac without having to shell out for a new computer.If you’re using a Late 2015 iMac and want a significant performance boost, I highly recommend this OWC RAM upgrade. It’s a cost-effective and easy solution to keep your system running smoothly for years to come.

I upgraded a 27" Late-2015 iMac from original 8GB (2 x 4GB RAM) to 32GB (4 x 8GB RAM). The computer is now fast again. No latency or maxed out memory resources. I can run multiple apps at one time again without the computer stopping or forcing to quit an app that is not responding due to memory conflict.These OWC cards are perfect for this application. Install took just a couple minutes. Should have done this long ago. I have effectively a new iMac for less than $75.

I installed the 2 x 8 GB cards into slots 3 and 4 after moving one 4 GB card into slot from slot 3 to slot 2 on my late 2015 27 inch iMac. Thus far, I have had no problems and the OS recognizes all 24 GB (2 x 4 GB original + 2 x 8 GB OWC cards) and boots with no problems. I'm not sure if the ordering of the memory cards is important (and neither was the Apple expert I contacted over the phone help line), but my configuration worked for my system so there was no reason to experiment with other arrangements. The computer loads programs and web pages faster and I no longer get the error messages that I am low on memory. Bottom line: Without doing a rigorous quantitative performance analysis, this upgrade with OWC memory cards worked for me as expected and was a very cost-effective upgrade.

No problems at all installing in my late 2015 Mac Retina 27 inch. If you are still running 8 GB of total memory (2x4), I suggest you upgrade especially if you use Microsoft or Adobe software. I put the 2x4 into slots 1 and 2, and the new 2x8 into 3 and 4. Easy, just find instructions online. 5 minute job. Computer recognized the additional memory and now I'm flying with 24G.

This ram works great. I think it’s some of the best quality out there from the research I have done. I would give it five stars if it weren’t for the price. This is ddr3 memory, so really only good for older computers. At this point it should probably be discounted.