I find this to be the case:
Low: Decent temps
Medium: Better Idle AND Load temps
High: Better Load only, but noise is a bit too high for some people.
I run 4 Tricools on high, the 200mm fan on high, a 60mm and a 40mm fan, both maxed out roughly 4000rpm, 92mm freezer cpu cooler fan @ 2800RPM, the 7600GT fan....
And I can't hear my PC over my window A/C Unit...