thanks for the advice, something i have noticed is that the all core boost seems to be around 4GHz and the single core 4.2 - not sure how to get these up to the stock numbers outside what I've already done.
How have you set up your system? First and foremost you should update to the latest BIOS since early BIOS' did not well support boosting for Ryzen 3000. Second but equally important would be to get the latest chipset drivers from AMD's web site and install.
Once you have that settled Global C-state Control, Processor CPPC, CPPC Preferred Cores, and AMD Cool'n'Quiet should be set to "Enabled" in BIOS. And of course, set up your memory and be sure Infinity Fabric is linked to memory clock speed. Leave multiplier and voltage settings on AUTO.
Probably not a problem if you recently installed it but you might want to run Windows UPDATE and let it install any updates for Windows. You want to get updated to v1909 which has a processor aware scheduler. You should be running either the Ryzen balanced power plan (installed with the chipset drivers) or the
1Usmus balanced power plan.
With all that set up you should be seeing it boost single cores to 4.4 Ghz and run all cores closer to 4.2Ghz in heavy loads. That cooler has a 120mm radiator so it will saturate pretty soon but you should get a few runs of CB20 before the clocks drop precipitously.
With those settings on my B450M Mortar w/3700X processor I can get scores 5025-5055 MT, and 490 ST. Tweaking PBO settings I can get it to 5145-5175 MT and 511 ST fairly reliably.
You get the best and most repeatable CB scores right after boot-up when the processor is still fairly cool, I usually make three runs to get the range. If you set it to run for like 10 min's let it run at least 10 loops on MT and watch clocks drop as the AIO liquid and radiator saturates. That's why temps won't get out of hand: the processor protects itself by dropping clocks and voltage as needed.
Also, as already mentioned your system has to be 'clean', nothing else running. The worst things to run are found in the system tray...you might have ICue or non-MS virus scanners that can drag down scores or just make them highly variable so disable or kill them before running.
Another way to help keep something from interfering is to give Cinebench 'real-time' priority in Task Manager/Details tab. When CB is running a multithread test the system responds to nothing, it appears locked. Just let it finish.