iMac 5K Late 2015 RAM Question

[SketchyClown]

So I have this Late 2015 iMac 5K that I bought gently used and it came with the stock 8GB of PC3L-14900S 1867Mhz Micron RAM. The guy I bought it from also included a 16GB (2x8GB) kit of extra RAM with it, but he claimed it caused issues so he didn't have it installed.

I checked the specs and the problem was obvious. He had got some PC3L-12800 1600Mhz (2013 era) RAM, and obviously mixing the two is a no-no. But I had some extra 1600Mhz/12800 Apple chips laying around and I found 2x4GB matching ones, so my iMac has been cruising on 24GB of the older RAM.

I have access to a couple matching (2x4GB) Micron 1867 chips.

So here's my question, 16GB of the newer 1867Mhz RAM the iMac came with, or 24GB of RAM from 2013?

I don't know much about RAM other than "more is usually good", so I am curious to other's opinions.

 

[mreg376]

The only right answer if you want the best performance and reliability, is to stick the the exact RAM specs for the machine. And while more RAM is better generally, depending of how you use the iMac there may be a point of diminishing returns.

What I do, and YMMV, is buy the minimum RAM from Apple, buy any additional I need elsewhere, and then wait for good prices later on to max out the RAM.