Maybe Change the orientation of your cpu fan? Im not sure how the HSF works since ive never had one but you should try pushing air from the the front of case, thru the ocz to the rear exhaust fan. See if it helps any?
Also, Ive never understood how HSF's in general of that style are supposed to work properly.... with a single fan the air comes out in 3 directions - meaning with one fan on one side of the HSF, the hot air goes out 3 different ways. This makes the airspeed much slower going through the HSF since the air can just enter from the "front", pull a quick turn upwards or downwards, then exit the HSF again after barely hitting the fins of the heatsink....
What you might also try to do is use two 120mm fans in a push/pull combination on opposite sides of the HSF and tape of ziptie on a couple of pieces of plastic to prevent the air from escaping out the sides. This should create a better "wind tunnel" effect and make sure the cool air running into the HSF goes across the full length of the fins before exiting again at high speed. Should improve the performance bit a good deal.