check the fan curve and see if you can make it a bit more aggressive.
im not sure but i recall hearing issues of the 390 from gigabyte being a hot card in general.
if Intel decided that the 5820k should be binned for different speeds and not just cores and you got a chip that was running higher then yes, someone didnt do their job properly.
the speed advertised by Intel is the minimum advertised specifications
So yeah, ill probaly stick with the plan of using Ryzen cpus for our workstations.
The power consumption coupled with the higher temps is really off-putting.