I have a case that comes with a side CPU duct. Problem is, I would only be able to use a low profile cpu cooler (something like the stock cooler). My question is: would it be better to use a smaller, "weaker" cpu cooler with a side duct venting in fresh air; or would it be better to use a larger cpu cooler without the side vent? Would the fresh air offset the better cooling power of the larger heatsink? I'm comparing say, the Zalman CNPS8000 vs. the Zalman CNPS9500. Thanks