I have a 3900x on an MSI pro carbon AC B450 with the Scythe Mugen PCGH and 6 case fans (3 side intake ML120, 3 top exhaust Noctua 120mm redux 700rpm) in a Lian Li O11 dynamic case.
All core OC at 4.2 GHz @ 1.25V leads to idle temps around 46C and sustained load temps of 80 to 81C with AIDA64 stress test for 10 minutes. It's good enough for a quiet cooler although at full boost the ML120s make a bit of noise but nothing too bad.
I would consider a 360 AIO for lower temps at load but the Mugen PCGH is running quite nicely.