Most people don't understand that there is no software available to accurately measure the TCase temperature. This specification has always been intended to be used by system builders that are building computers by the thousands.
To accurately measure TCase you need to cut a groove into the heat spreader on top of your CPU. You then have to mount a calibrated thermocouple to the geometric center and solder this into place. Grind it down so it is flush and now you are ready to measure the TCase temperature of your CPU.
Intel does not want individual users hacking up their new CPUs with the Dremel or taking their CPUs to the machine shop for this procedure. For end users they decided to mount temperature sensors at the hottest spots on the core. ie. these are known as core temperature sensors. These sensors are built into the CPU and the information they report has nothing to do with the TCase specification.
As the cores heat up, these sensors will count down to zero. When a core reaches zero, this will trigger thermal throttling, your CPU will then slow down and reduce the core voltage to prevent it from being damaged. As long as your Intel CPU is not thermal throttling, it is running with in the Intel design spec. If Intel thought this was going to hurt your CPU it would be simple for them to lower the thermal throttling temperature.
You can run RealTemp and look at the Distance to TJ Max data. These are direct readings of your core temperature sensors. If it shows a number bigger than zero and and the Thermal Status area shows OK, your CPU is running within spec and there is no need to worry about its temperature.
Thermal throttling and thermal shut down are controlled by core temperature data. TCase is a useful spec for system builders that are engineering heatsinks and deciding what size and speed they should use when choosing a case and some fans.
Edit: TCase is definitely not 105C for any CPU. The 45nm Core 2 Duo CPUs had a maximum core temperature of 105C.
Here's an example of a CPU that is very hot but it is still running at full speed because it is within the Intel thermal spec.
http://img27.imageshack.us/img27/6216/torturetest.pngEdited by unclewebb - 10/18/13 at 5:16pm