have u tried fitting a fan on the other side of the cpu heatsink the concave side...both fans pushing air to the back exit fan on the case...
yes i have tried fitting another fan to the other side of the titan cooler , did not seem to make a difference ....someone on the forum said they had fitted one and had made a difference ...only thing is you need 2 matching fans ...i tried a slower fan , 1400rpm compared to the titan fan 2000rpm
would not bother if i was you