I've designed passive cooling for outdoor LED products but am not a thermal expert. The comment: "With your suction fans, you are just likely pulling the warm/hot air out of the iMac faster than it would have normally exited.." may seem like a conceptual challenge. It is, however, exactly what I wanted to do. Speeding along the already flowing air will increase volume moved and therefore remove more heat.
I did not pursue a "bottom up" push of air. It would have required very tight ducting to push the air into the narrow inlets. Think of pushing on the end of rope....without tight control along the edges of the rope there is nothing gained. I sense air is an elastic medium and in this application instinct spoke: "better controlled by pulling, not pushing". The tight bottom ducting would have required a lot more precision and time than I was willing to invest - noise and spill air (maybe even hot air) would be at my work plane (table) and "in my face". The rear top design is visually pure to me. The noise and airflow is directed backwards, a real plus in my mind. So far...so cool. I appreciate your comments.
PS: If others are fighting the same thermal battle and would like more details regarding the construction of my apparatus, please let me know.
