Ok, thanks for your (und @F|Marsman´s) Comment.
After 5-6 reboots, my machine would not start again with 3933MHz, feels like the old cold start Bug.
So I am back to 3733 and played with the Timings, so this is my preliminary result:
VDIMM is now at 1,5V
Temps are around 50 Degrees at Testmem