He obviously has an Intel CPU since AMD CPU doesn't have individual core sensors (it actually doesn't even have core temperature sensors, the sensors on the north bridge). According to Intel tech documents the internal sensors of the Core/i CPU's are only very accurate at high temperatures (ie. near its thermal limit). At around 50C the sensors can be a 5-10% off, the accuracy increases to within 2% at the thermal limit (TJmax). So your temp of 60C could really be anything from 54-66C which is within the temps of the other cores.