So, it appears that my machine is running pretty hot with this upgrade. It has been over a month since I've done the upgrade, and everything was fine in the beginning. In fact, my machine was reporting better CPU temperatures then. Now, however, the CPU temps are up - and, most importantly, the Northbridge chip (the chip itself - not the heatsink) is currently resting at a hot 169F, with fans all at default speeds. Ambient air is 88F, and room temperature is ~75F. I am not seeing anything unusual or resource-intensive running. Additionally, a while back - while still at eight cores - I cured my Nb chip of its overheating issue, by replacing its plastic pegs and giving it new thermal paste. Still seems hot, though... What are your temps for your 12-core classic Mac Pros? I'm curious to see. These temperatures don't look normal. The Nb chip temps were higher from the start, but now my CPU A diode is at 120F with a few applications open.