You have CPU that runs at great temperature and doesn't require excessive and noisy cooling at stock. The temperature will rise exponentially once you overclock, for comparatively very little multi-threaded benefit.
The single-threaded performance is already maxed out in stock, there is no possible further gain, so you can only gain slightly bit faster render-time, but we are talking at best 12-15perc at point where you get additional 20-30C temps, which are unmanageable with Noctua and require some more serious cooling of which only one is currently on market (building your own custom water loop), and one experimental might come at end of this Q2, although I wouldn't count on it during the current crisis.
This is nothing like Skylake-X Intels where free 30+ perc. of performance is guaranteed.
At stock, the auto-regulated voltage is also managed very well, and will preserve longevity of the chip. Dies from 7nm node are extremely dense, and they do degrade with higher voltages that drive overclock.
This historically wasn't much the case for past decade but it is now and will continue with further progress towards even smaller node (5nm, 3nm...). I doubt this is worth it for 4000 Euro chip. I am also not sure what the long-term stability of overclocked 3990X would be due to fact that I/O die is also on the chip with Zen2 and is responsible for stability of the memory system.
3990X is the kind of CPU that you buy, install and forget about it. Need even more performance? Buy a second one :- ).
You can do a little bit of PBO by manually upping the PPT limit from 280W envelope to 300-320W, which will preserve higher turbos as long as the temperatures are managed (case with good airflow is mandatory).