why isn't the best cooling simply making a passive HS an active one?

[bleuless]

the sonic tower is a passive heat sink, but what if we make it active, will it stand up against and beat a tuniq or ninja? since it's original design was to make it efficient (to stand on its own ground) w/o a fan, now with help from a fan, i would imagine it would out perform other 2 easily.

 

[Talcite]

That may not necessarily be true. Heat transfer curves are not linear. One example is a comparison between the scythe ninja and the scythe mine I read a few months ago.

While the ninja performed better at low or near passive fan speeds, the mine performed better at higher speeds. I'm not familiar with the sonic tower specifically, but perhaps someone with it could do a comparison against another cooler?

 

[Fullmetal Chocobo]

Becasue passive heatsinks have more space between fins to allow more slow moving air to go through the fins. A design for active cooling has smaller spaces between the fins, thus increasing surface area for cooling. It's a trade of in design that differs for the application.