well i've done something very similar to this as well, for my gpu's.. i have about a 8-10 inch fan, i just angled it at the case so it shot stuff out the exhaust to keep heat out, it made my idol from 56 to 47 degrees celcius, which is amazing!!! it did a good job, but it gets rather dusty, so i wouldnt recommend it myself, only if its temporary for benchmarking or something