MonsterLabo's Beast case is able to maintain max temperatures of 89 °C for an Intel i9-10900K running at 4.5 GHz and 1.13 V on all 10 cores, while the RTX 3080 GPU required a bit of tinkering to prevent power leaks above 80 °C.
https://www.notebookcheck.net/100-passively-cooled-Intel-i9-10900K-and-Nvidia-RTX-3080-now-possible-with-MonsterLabo-s-Beast-case.574200.0.html