Similar behaviour to what I'm seeing on 5900x. It was a bit jarring at first because I upgraded from a Skylake quad core (i7 6700K) which idles at like 25 to 30C and ramps hard and fast to 72C under load. vcore varied from 0.4V to 1.25V and only really hits 1.25V sustained under heavy load while turboing. Base and boost clocks are not appreciably different. The 5900x and by extension, 5950x just seem to work differently.
There is a massive difference between base and single core boost clocks and the 5900x idles hot by comparison - 40C minimum and frequently single core boosts. So idle to light work loads will see temps swinging between 40C and 65C. During this time, vcore can twitch up to 1.4 or 1.5V.
But when its under heavy all core load it doesn't get much hotter really and vcore tends to go down because its not single core boosting all the time. 1.1V to 1.3V ish. 72 to 78ish ish when every core is under load at base clocks.
This is with an NZXT S340 Elite, Noctua U12A (push/pull A12x25s), stock noctua thermal compound, 2x intake (NF-A14 Industrial 2k 24V) and 2x exhaust (NF-F12 Industrial 2K 24V). So not by any means a rig built for stonking thermals. Most of this was taken from my old Skylake build except I went from a U12S (push/pull NF-F12s) to the U12A.
Inclined to believe this is normal behaviour like others in this thread, just different to what I'm used to from previous builds. Then again, this is the first time I've ever had more than 4 physical cores on a desktop so still learning the new behaviour.
The frequent, massive boosting in light work loads meant I had to redo my fan rpm curves. Longer hysteresis so fan rpm ramping doesn't track the boost behaviour closely, resulting in frequently "dustbuster" bursts when idling which sounds annoying. Its ok to let it briefly and frequently shoot up to 65C at idle/light tasks at low constant fan speeds and it seems to handle it well. It doesn't boost up and stay up so idle temps and vcore fluctuate a lot but it seems fine. I didn't get much peace of mind though until I saw loads of other people reporting similar observations.