After several weeks of testing, I experienced some stability issues, especially on Assassin's Creed Origins.
Ok ok, some crashes were linked to game itself, but it was patched and crashes frequency reduced drastically...however there were still some random crashes.
Due to the crash nature (game is closing), i suspected RAM instability.
Thus, I took the time to test my RAM using memtest64 (1 hour without error was my benchmark) that is really useful.
Indeed my RAM parameters were wrong, I got some ram errors quite quickly.
I tested several parameters (some failed after 50 min...
) and I went to those final numbers :

At the end, I'm back to a stable 3200Mhz 14-14-14-14-34 but with lower subtimings.
I found these parameters OK for a fully stable setup.
It's like my 4.0Ghz OC I can run higher for benchmarking when required..