Overclocker's Australia has a sweet little review of some new technology Y.S. Tech has developed. I don't know how they will perform but they look pretty sweet. Basically, what they've done is made a fan that is driven, not by a central motor as we're used to, but by an electric motor around the OUTSIDE of the fan.. using the tips of the fan blades, this should eliminate the dreaded 'dead zone' in the middle of a HSF combination. This could be a real improvement but I sure would like to see some specs on this.
Here's a snippet from the YSTech site:
"COOLING POWER It reduces 75% of traditional motor hub area. This revolutionary breakthrough not only increases 30% of airflow and static pressure, but also brings air stream directly to the centralized heat source. As a result, T.M.D. FAN improves the efficiency of heat dissipation at least 15%.
POWER CONSUMPTION / TORQUE Locating motor at 4 corners substantially expends the room for winding. Thus, lower power consumption can be easily attained. At the same time, the torque of motor becomes even much more powerful than ever.
ACOUSTIC NOISE / BALANCE As known, the tips of fan blades are the main source of noise when a fan is rotating. The magnet of T.M.D. FAN surrounds along the tips of fan blades. This "tip-magnetic" design eliminates the major noise source of an impeller and provides the suspended balancing force when impeller is rotating."