The fan is definatly not the problem (its actually the best possible fan you could have used). I would think the problem is either one of two things: either you put on too much compound (you litterally need a translucent coating on the cpu), or the contact pressure is too little (ie the heatsink is either not screwed down enough or its not equally pressured so part of the heat sink is off the cpu). I would suggest taking out your motherboard, taking off the heatsink, cleaning both the core and heatsink thoroughly with some isopropyl alcohol, reapplying a razor thin coating of as3 (also i like to put a VERY small dab on the heatsink, rub it on the contact area between the heatsink and cpu, then wipe off the excess), and then making sure that the heatsink is mounted perfectly flat and that the heatsink is snugly on the cpu.