There are XMP profiles that are not set correctly or being misread. For example, XMP reads tRC as 85 when infact it should be 58. I Would fully recommend using Ryzen Dram Calc. However it is not for use with all ram revisions. You can use Thaiphoon Burner to read both the IC die you have (Samsung B-Die Hynix CJR/DJR Micron Rev-E) under Die Density but also have a look at bottom left where it says revision it will say something like "B1 or A2" this is your Dram PCB Revision on Dram calc.

I have found that some are missing on there though such as the bad die, high timings that is currently being released as Samsung B-die (19-22-22-42) There is also Hynix B1 DJR that I have found to be the same as B2 but slightly better (tRAS) If you find you find it matching the stock primary timings with your current ram at the stock speed. Great. Its working correctly and you can tweak it for increased freq and tighter timings.

I Recommended changing Fclk if you change up beyond 3600mhz. It is possible on most 3900/3950x to get 1900fclk with the help of tweaking the rest of the ram settings and the SOC/VDDG/VGGP voltages. If you find things crashing or memory errors from the membench You will either be looking to increase voltages (Soc VDDG/P & Ram) or simply you cannot run the timings so low and need to increase to a point its stable and error free.