For Raspberry Pi4 continuous selfhosted server operations: with and without case fan. This graph show a 20°C decrease, with a slow rpm fan.
The metal case has thermal stickers to reach for main components on both sides, and the fan is what I have in scrap parts, totally not for that case but pushes a lot of air with low noise compared to screaming mini cpu fans.
That is one beefy fan for a rpi.
I’ve just got a case similar to this; but all snap together, no screws:
The fan runs off the pin headers. Meant for 5v, but I use the 3.3v line to run it a little quieter/slower.
Even that makes a good 10°c difference.