I just upgraded the CPU on my Mac Pro 3,1 from a Q2.8 E5462 to a Q3.2 X5482. I didn't go with dual processors because I wanted faster single thread performance, and the upgrade from single 2.8 to single 3.2 was only $25. However, the Q3.2 I installed seems to be running really hot under load. My old E5462 ran at 40 C idle, 56 C under 100% load on all 4 cores. The new X5482 runs at 42 C idle, and 79 C under 100% load. However, the CPU heatsink temperature stays about 44C during 100% load. The computer doesn't appear to have any issues with throttling, but the high temperatures concern me. AFAIK the TJunction MAX for the X5482 is 85C, so I'm getting awfully close to this. I'm reading the temperatures of the CPU die and heatsink using temperature monitor lite. Does this sound like a poor application of thermal compound? I'm using Arctic Silver 5 with the "line" method covering both cores under the heat spreader. The computer has only been through 3 thermal cycles and about 30 hours of use since I replaced the CPU. Do I have to somehow recalibrate the thermal control system after I installed the new CPU? After installation I did reset both the SMC and the PRAM. Or do these CPUs just run really hot? My main concern is that while fine now, running this hot will melt the CPU in 6 months. Does anyone have any experience with the E5462 -> X5482 swap that they would like to share?