I have a first generation Macbook Pro (core duo 2.16ghz) and I have been keeping track of the temperature sensors lately to get an idea of how hot it runs under different loads. I plan on keeping this thing for as long as possible so I want to know when something starts to go wrong. I have been using a program called temperature monitor as well as istat pro. Everything seems to be running at normal temperatures for this old model under idle conditions. The weird thing is that under high CPU loads (encoding videos mostly) the sensor labeled "CPU A Temperature Diode" is much higher than "CPU Core 1", "CPU Core 2" and "CPU A Proximity". For example, with an HD netflix video playing the cores and proximity are all 64C +/-1C and the temperature diode is 79C. Under nearly 100% CPU, the cores and proximity get up to the high 70s and the temperature diode can surpass 110C. When the load stops the diode falls very rapidly to its idle value. Here is a graph for an test of 100% CPU. The diode temperature is obviously the high one and the other CPU ones are the ones below (not the straight horizontal ones, i dont know what those are). It doesn't make any sense for the difference between the cores and the diode to be so great considering there locations are so close on the chip. Clearly, the temperature reading is wrong and it is somehow being scaled. I have searched around and have found nothing. I have noticed on another computer that the cores and the diode are usually the same temperature (+/- 2C) under all conditions. I have no concerns about any actual overheating but I am concerned that the computer will shut down automatically if it is sensing such a high temperature. Does anyone have any idea whats going on and how to possibly fix this?