Putting it between the fins would yeild highly inaccurate results.fade2green514 said:id say right in the heatsink, between the fins.... preferably right near where the clip holds the heatsink down, it pushes straight down on the processor. that'd probly be where the most heat is.
as helmie said, it won't be very accurate, depending on how well the heatsink is applied and such (bad thermal compound application = no heat getting to the sensor)