There are 2 rigs here with R7 5800x CPU both on a B550 board with 32GB RAM... one will run at 4+_ Ghz right out the box the other will not run past 3.6Ghz. Both use Wraith Stealth coolers with temps <= 56C.
Question: why won't one turbo boost .... have Ryzen Master .... but I don't want to do complicated tweaking as the CPU should hit 4.n Ghz automatically...
(have a R5 5600 that boosts to 4.1Ghx when needed).
both b550 or both exact the same b550 mainboard with the same bios version?
The culprit was unexpected. It wasn't about the bios or any of the usual settings. The culprit was the third party "speed enhancers" that had apparently set a cap on the CPU speed. I have Samsung magician, which has a performance setting, and I won't name the other applications that seem to insert their performance enhancers into the Windows power settings.
I deleted every one of those and reset the power settings to "balanced", and all is well. Now the CPU routinely runs at 4 GHz +.
Ryzen master is actually pretty good and I used it on numerous occasions trying to address this and on one occasion I used the Ryzen master manual setting, and the CPU ran at 4 GHz +. The thing is that the Ryzen 5000 CPUs auto clock on their own and you don't have to do anything unless you want to tweak it or do some kind of bench marking effort.
So the solution for me was to go into Windows power settings and delete all those other power settings except for the ones that Windows 10 provides by default.