Fans pull from the side, not the center, so only the upper edges of the fins would get significant airflow. I know this to be true and can use a real life example: Many "weekend warrior" racers have tried to clean up their engine compartment and ease the replacement of belts by leaving off their fan shroud, only to find it caused the car to overheat.
Alpha actually made shrouded CPU coolers that would pull air all the way from the bottom because of the shroud, but they still pulled air from the sides, not the center.
A blowing fan will cool everything except the "dead spot" under the bearing. It will in fact cool right down to the base, as air hits the base, swirls, and is mixed with other air that's being exhausted.
Another problem with Alpha's design was that it pulled IN all the heat from the chipset and VRM components, since it pulled air from close to the board. Many people pointed to the cooler's performance to vindicate the design, but those coolers only gave good performance because of things like surface area and copper bases (unusual at the time), even with the shroud testers found that turning their fan around (to make it blow like normal coolers) gave them a temperature improvement!
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