i just did this mod to my friends computer and i took all the temps from everest and the bios before and after but there was no temperature change only 1 or 2 degrees. the only thing he had was a 80mm rear exhaust and a cpu and
psu fan, the cpu fan one of those vent things built into the case side. i put in a 120mm fan right under that mainly for the gfx card and a top 120mm exhaust. but not much temp drops ?