Welcome to TPU!
Where is the best place to install a temperature sensor on a processor, My coupter case has a temp. gauge built in it. need to know where the best place to put the sensor on the CPU or on the Heat Sink and what to use to hold it in place.
That's a loaded question.
The tech documents I have from AMD actually recommend machining a tiny channel into the heatsink and then putting the probe in the channel.
Another option is to drill a tiny hole near the base of the heatsink and insert the thermal probe with some thermal paste.
The easiest, and least useful thing, is to attach the thermal probe with some
thermal tape as close to the CPU core as possible.