on my HAF I have a 120mm red antec trilool attached to the top three drive bays using screws, and under that I have my dvd drive. I'm considering making a plastic deflector thing to push the air coming in downward, so that it doesn't just immediately get sucked out the top vent/fan. I'm not actually too sure what the problem your describing is though tbh.
Btw, anyone know of a good way to light up the HAF a bit? My front is all glowing red, but the inside of the box is dark and I would like a bit of light to see whats going on in there. I don't want a mess of cables though which is what I got when I tried dual cold cathodes years ago.