It's the law: Heat always travel to cold, or the flow of heat is from hot to cold. Since the cpu is the hottest, it's heat is given up to the surrounding 'cooler air' the warmer (somewhat) air from the cpu, is pushed by the fan, to the cooler outside air, where in my case the cabinet, starts warming up. If the cabinet, can not remove the warmed air, then the cpu runs warmer. My cabinet has a side mounted, fan, which has its own thermostat, the fan by itself was not able to remove enough heat. So cabinet temp. was always rising, despite its effort. On the top of the cabinet, I put a 10" long (sorry Bill, not in centimeters) vent, but this was in the path, of the fan. So when the fan came on, it would suck, outside air, from the vent, & dispel it out, via the exhaust fan. Next place a large vent at the bottom, of the cabinet, source for cooler air, to enter, which also, lessened the resistance air flow, for the small fan. Next I made a small cover for the top vent, so as not to short circuit, air (air moving in from outside due, pathway vent/fan proximity. Rummaging around the attic, I found just, the right ticket. Seems and old leaf blower, had an attachment, never used for vacuuming leaves, which had a approx 6" diameter (sorry Bill inches again) PVC like, angled (30ish degrees), piece (kind of like stove pipe, but pvc. I took a bracket attached it to the PVC & then attached it to the side wall, totally enclosing the fan, now where the fan gets it's suction air, is not in the path, of the top air vent. Now no matter how hot the box stays cool 84F, & the fan works way less. Just a tad obsessive Fun fact: Physicists, will/can explain there is no such thing as cold. Cold is merely what your left with when you take heat away. Cold is not real, what you feel is the absence of heat I would venture to say this, thinking came from the 'big bang' which was not a cold explosion.
