CPU Proximity Temperature & CPU Die Digital Temperature

A die in the context of integrated circuits is a small block of semiconducting material, on which a given functional circuit is fabricated.

Obviously heatsink will be cooler all the time then CPU itself. So look on CPU Die Digital and don't let it go over 100 deg. If this happening - your cooling system can't handle your CPU performance and you should slowdown for a moment.

The i5 processor has a TCase value of 72.6°Celsius; anything from the Tcase and below will be the expected temperature of the processor in normal use, anything that doesn't stress out the processor like watching movies, burning CDs, browsing the internet, creating documents, etc.

When the processor is stressed out and it is being use at 100%, the temperature will go beyond the Tcase. It can perfectly reach 80 to 90°Celsius and the processor will still be OK. The cooling fan is in charge to keep that temperature there.

If the temperature reaches 100 °Celsius or more, that is consider overheating.

I assume CPU proximity is the CPU heatsink. CPU Die is the same, CPU Die.

Download Intel Power Gadget. You'll probably enjoy seeing your clock frequency vary and, being the manufacturer of the CPU, it'll probably give you the most accurate numbers. Note that the CPU monitors itself and will throttle the clock speed back when it reaches its max rated temperature. Personally, it concerns me that the SMC uses the proximity sensor rather than the die sensor to control the fan speed.