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.
The CPU is perfectly happy sitting at 50°C. It is slightly happier at 30, but it doesn’t actually help in any way unless you run into throttling, or run (much) hotter for longer. It’s fine.
Some might state that the CPU is probably gonna live longer, but seriously have you ever had a CPU die on you cause it was old (or even die at all, even)? Again, it’s fine.
Having something that mostly agitates the air (not even really moving it) like a low-hundreds-rpm fan would also work. As would using one of those passive heat pipe coolers that are also overkill (especially with a fan, but just leave that off), but have the same “number looks better” effect.
@Creat When I said I had one Pi lifetime that was shortened it was a way of saying yes, it died from 24/7 high load no fan overheating. Now it just boot and freezes after a couple of minutes.
Then, yes, back in the days when overclocking and over powering was a thing, CPU actually died from all that, I changed a few for customers that didn’t know better. How ironic I did that to myself years later with little arm boards, isn’t it?
That’s what I said with “much hotter for longer”. If it’s constantly thermal throttling, that’s gonna be an issue. Of course OC’ing also will. 50°C just isn’t an issue. Also older models have CPUs that either don’t throttle at all, or do it less well/effectively.