thanks Chino, all that is already done: bios is 160,1 all the memory is MemTest86+ tested and stress is no issue as the system crashes at low load or idle.
I didn't change the voltages yet as Nate152 suggested.
the reason for that is, I lost already two month with quite chaotic and not really structured troubleshooting.
now I want to do it right, doing a test until I'm sure about the result.
after my last crash I set the rams on SPD and they still run with no issue for 8 days now.
if I change something right now I won't be sure that the rams run error free on SPD.
it's the damn randomness that makes me crazy and I can't be sure about a test if it's shorter than a week to 10 days.
same will happen after I change the voltages, I'll have to wait at least a week to be relatively sure.