Measure your system, e.g. Zigbee thermometer for your actual room power draw so the plug for your entire system, computer obviously but also screen, speakers, etc even AirCo unit or physical fans if you have some for the room itself.
That’s the only way to know what is actually happening.
If you do not want to go down that path then the heuristic is simple : the heavier the load on either CPU, or GPU, or obviously both, the higher the temperature. If you have a dynamic system, anything built this last few decades or so, then the fans will not kick in under a threshold which you can consider won’t significantly heat up your room.
TL;DR: if you start to hear fans spinning, you have to reduce your load.






Artwork idea : load thermostat.
You can’t start a new application if your room is above a temperature threshold.
Extension artwork idea : load credits.
If you do delegate some load to a non digital form, e.g reading a paper book instead of watching a movie, then you “earn” some credits you might use to bypass the load thermostat “when you really need it”.