I just put this system together and was confounded by my 3900x temps. Idle temp was high and frankly "cpu" temp it didn't really seem to respond to load in any sort of useful way. (making a good fan profile was laughable)
I started experimentation and found that the "cpu" temp had really nothing to do with the core loading. It was mostly memory and IO related:
Idle at 59-63*C, Mem at 1.38V, 3800MT (XMP)
Idle at 51-55*C, Mem at 1.25V, 3800MT (XMP)
Idle at 41-43*C, Mem at 1.20V, 2400MT
Idle at 39-41*C, Mem at 1.10V, 2400MT
Loaded 78-81C and slowly climbing, Mem at 3800 MT (XMP) 1.38V
Loaded 71-80*C and slowly climbing, Mem at 3800 MT (XMP) 1.25V
Loaded 68-71*C and slowly climbing, Mem at 2400 MT 1.2V
Loaded 65-69*C and slowly climbing, Mem at 2400MT 1.1V
My past experience says pushing a silicon chip connected to a metal heatsink results in a increase in temp over time. With this 3900x, the reported CPU temp increase and decreases instantaneously with load. Really! instant on both the up and down slope... crazy.
IMO this could only happen if the CPU temp was either A
not connected to a heatsink, or b
some sort of fake algorithm.
When you have three chips making up a "CPU" what do you report as the temp? ... AMD has clearly messed this up somehow.