As long as software can report temperatures within a few degrees, that's fine. The closer a core is to the TJ. Max., the more accurate the temperature reading is (as long as the software is based on the correct TJ. Max. value, etc.) The primary goal is to protect the CPU, not to provide very accurate temperature readings. The CPU will shutdown way before it gets damaged. I know because a fan failed on one of my systems and it shutdown a few times before I realized that the fan wasn't spinning at all.