I had the same issue on day 1 of my build, the fix, which I found here, Change from Ryzen Power Plan to Windows Balanced Power Plan. My temp dropped down from 55-60c idle to 35-40c and gaming from 90-95c down to 75-80c max after 4 hours of gaming ( it runs at 65-70c in the first 2 hours of gaming).
Give it a try see if it works.
edit:
Build:
r9 3900x
1070ti
samsung evo 970 500gb
gigabyte aorus x570 elite
bequiet 700w PSU
hyperx predator black 16 gb 3200mhz.
I don't know if this change of power plan had something to do with PC suddenly not starting after 5 days ( all fans spining, no error beep codes, RGB on MOBO and GPU doesn't light up ) I sent my mobo to warranty and still no answer.