So today I decided to swap out the main fan in my MDD. I didn't like that my CPU temps hovered at 54-58*, even with Arctic Silver 5 and the slightly better heatsink. So I removed the factory Delta fan, and installed another fan the same size from another PC I had. Only difference is the new one has a higher CFM, and I hooked it up to direct (full) power instead of the logic board. The result? A 10-15* drop in CPU temps, which makes me happy. Plus it's slightly quieter. Now the temps are 40-45*. I DID try the factory fan with direct power, but it was enormously loud. It ran at 35-38*, but it was simply too loud to be a good tradeoff.