One reason to use these is if you are using a motherboard that
doesn't have fan connectors. This is very common among the proprietary
motherboards used by companies like HP, Compaq, etc (they use
large heatsinks and a duct system that drags air across the
processors). Sometimes you want to add a fan for better cooling.
These are also useful for certain proprietary motherboards that
use odd 4 connectors on the motherboard (some Gateway motherboards
are like this).
Kwad