12GB OWC DDR3L SO-DIMM PC3-14900 1867MHz CL11, 1.35V Dual Channel Kit (1x 4GB + 1x 8GB) by OWC

Upgrade the memory in your 27" iMac with Retina 5K Display (Late 2015) with a model ID of iMac17,1 using the 12GB DDR3 1867 MHz SO-DIMM Memory Kit from OWC / Other World Computing. This memory kit features a total capacity of 12GB, which is made up of one 4GB Module and one 8GB Module. It also has a clock speed of 1867 MHz, a bus speed of PC3-14900, and a 204-pin SO-DIMM form factor. It operates using 1.35V, has a CAS Latency of CL=11, a cycle time of 1.875 ns, does not support ECC technology, and is not registered. Additionally, it is fully compliant with JEDEC specifications and is RoHS certified.

Compatibility:  Late 2015 iMac 27" with Retina 5K display: 

iMac w/Retina 5K display
(27-inch Late 2015)
(October 2015) 
Model ID: iMac17,1
3.2GHz i5, 3.3GHz i5, 4.0GHz i7