I like how you went with the $2 USB fans instead of the pricier ones that seems so popular among USB miners.
the pricier fan is by far more powerful. got one of those cheap-o fans to, they suck.
If the heatsink is of the correct design there is no need for a howling gale to keep it cool. All I need is steady air movement,
my heatsinks reduce the chip temp by 16C. I tested the boards with and without heatsink at the factory (and that was passive cooling).
cheers,
kev