Your spec is very similar to mine, and it ran just fine. Although my ram is 3600 cl16 and my 3900x is apparently 'silver'.
I wonder what the differences are with people who get it to run and people who don't.
Yeah, it's odd.
The diag part runs fine and gives me the possible settings.
When hitting start CB20 runs fine and logs a score but it's when it goes on to do the testing that at some point it will end up just restarting the PC.
I've messed about with all sorts of settings and all I can seem to get it to do is change the length of time before the PC restarts and it's always just a hard power trip restart.
Even with the mem, my manual timings don't work, nor xmp, even setting the mem to 3200 and leaving timings on auto (where it booted at something daft like cl22 !) don't help.
Might try just setting the 4375MHz/1250mV or 4200MHz/1150mV the diag part recommends and see if that is stable.
edit: what did you go for for LLC in the end - assuming you have the same mobo?
He did tweet to ignore the LLC warnings in the log but the documentation seems to contradict itself.
I tried pretty much all the settings but medium seemed to be the one where it didn't complain about it in the diag run.