holes on the heatsink use a standard 92mm fan, and doesn't have to be super-high flow.
Actual power usage is under 45 on all of mine, more like 40 even on the no-fan ones, using bricks I got from Zoomhash.
You need to put a big thermal transfar pad between the PC board and the heatsink and screw them together - that the ONLY cooling the chips get, and they will NOT stay cool without good solid thermal contact.
IMO the termal design of the "blades" was very very poor.
Also check into the threads on litecoin talk and here about adding heat sinks to the regulator circuitry - or UNDERCLOCK the board - that was the biggest fail point on these miner boards.