Timetec Hynix IC 16GB DDR4 2400MHz PC4-19200 Dual Rank SODIMM Memory Compatible with iMac Retina 4K/5K 21.5-inch/27-inch Mid 2017 (16GB)

2017 5k 27" iMac installed with 4GB cards in slots 1&3. I removed the original cards and installed the 16GB cards into the same slots. Restarted, no problems. I shut down again, and installed the original cards into slots 2&4, bringing total RAM to 40GB. Restarted, and again no problems. Installation was simple and straightforward. These are excellent RAM cards, made in USA, not China.

I tried a different ram sticks that were fitting the apple requirement but there were ongoing troubles with installation and pain before it started working (with some workarounds and a lot of internet research). Still I could see that the computer isn't very happy so I sent it back and ordered this Timetec instead, as I have a great experience with them from the past (and the two original 4gb sticks seem to be from the same company as well). Fits without any troubles, works smoothly straight away and the computer is very happy, strongly recommend!!! :)

Initially I had some issues. I ordered 2x 16GB cards to add to my 2017 iMAC which had 2x 4GB cards - to bring the total to 40 GB. Initially I could not get the iMAC to Start after putting the 2 new cards in. I tried various combinations. Thankfully Timetec support was prompt and helpful. First put the new cards in the slots where the original cards are (mine were in Slot 1 and 3; remove originals and put them to one side) and start the machine with only the new cards. Once it is running with the new cards in these slots then you can shut down and put all four cards in together. I finally put them in the following configuration. Slot 1 4GB, Slot 2 16GB, Slot 3. 4 GB, Slot 4 16 GB and it works fine but you MUST follow the first step described above to get the new cards working!

Very good, will recommend it to others

Upgraded from a 8Gb to 32Gb.. on an old 2017 imac.. not a great difference in performance.. but at least it can now handle multiple tasks without any hdd swap memory being used..

Used in iMac 2017 and all good. Went from standard 2 x 4gb to 2x 8gb. No issues with install just took old ones old and put new ones in the same slot. No config needed. Does seem faster and improved performance but Mac still slow. Now I know this is due to the Mac not the memory.

New memory arrived next day as expected (as per Prime delivery details). Easy to install and worked straight away in iMac 2017 27inch system with no issues encountered. I wanted the extra memory in order to run a number of virtual systems and have not been disappointed.

Does what it says on the tin. Took me about 5 mins to install (followed you tube vid). Recognised straight away. I ordered to 16gb sticks, I left the existing two 4 gig sticks that were already in my mac, taking me up to 40. Jumped now after waiting over a year for the price of ram to come down.