Yep, understood. We're on the same page then, I just wanted to be sure you understood that tooThe temps I'm using are being reported by aida64, but the temps I'm going by are the CPU diode temps. Aida64 and other programs will also report the "CPU temps" which are usually lower. (the diode temps are supposed to be from the cpu package, where the "cpu temps" are read from the mobo socket).
So in your scenario, Aida could have been giving you the cpu socket temps, where Afterburner was giving you the diode temps. Ryzen Master uses the diode temps AFAIK.
75c seems totally fine in your case, and mine, barring room ambient factors. Quick google, and I see most reports online between 65-80c, depending on delta.
The only other 3900x owner I know of that deep-dives in to this stuff is @lowfat but I'm not sure if hes still manual vcore maxing CCD & overclocking, so he might not have much to input...
I gave up doing that, as the idle power use vs performance gained wasnt worth it in my use case.