I recently bought an Opteron 165 to replace my old Athlon 3800 X2. The old 3800 X2 was cooled fine by my Cooler Master Hyper TX2 cooler. The Opteron on the other hand is getting mixed results. One of the cores cools quite well while under 100% load, the other not so much. On the first core, it doesn't go higher than 55 degrees Celsius with Prime95. The second core on the other hand is getting as high as 74 degrees Celsius. No matter how many times I've re-seated the cooler, my results are exactly the same. The AS5 grease is evenly coating the CPU heatspreader, so my guess is that I may need to consider a new cooler. So I need suggestions. I have an Antec Solo mid tower atx case so it needs to be able to fit in there without clogging up it up, and I can't spend more than $40 at the moment. Due to my DFI NF4 Ultra-D board I would also like to know if a top fan cooler would be better than a side fan cooler. Thanks for your suggestions!