Chosen Solution
Can I leave the existing DIMMs that came with the system (2x4G) and add an additional 2x16G DIMMS for a total of 40G? Do I need to place all the DIMMS in matched pairs of slots?. For example the 4G DIMMs in slots 1 & 3 and the 16G DIMMs in slots 2 & 4 or can the DIMMS go in any slots (4G DIMMs in slots 1 &2 and 16G DIMMS in slots 3&4)?
Yes, just add them in the empty slots. RAM Type:PC4-21300 DDR4 Min. RAM Speed:2666 MHz Details:Supports 2666 MHz PC4-21300 DDR4 SDRAM SO-DIMMs (260-pin). Standard RAM:8 GB Maximum RAM:128 GB* Details:*By default, 8 GB of RAM is installed as two 4 GB memory modules (and two slots are unoccupied). At the time of purchase, Apple offers custom configurations of 16 GB, 32 GB, and 64 GB of memory for an extra US$200, US$600, and US$1000, respectively.
https://www.kingston.com/dataSheets/HX42… Is such a memory suitable?
