Hi, i bought a ryzen 5 3600 2 months ago, and it haves been great, but i was doing some testing and stress on the cpu and it never goes further than 4.000 mhz
For all core load this is just normal. Did you check singlecore load or even idle frequencies?
On stress it wont go further than 4000, on idle i have seen it up to 4.199 on hwmonitor