I'd try something like enable DOCP / XMP and try 16-18-18-36 @ 1.35V
If that doesn't work, maybe 18-18-18-38.
If that doesn't work, pull the 2 mcron and test at XMP and then pull the samsung and test the micron. You may only be able to run 2 sticks in A2/B2 slots.
Sounds like it's not a...