ThrottleWatch is a utility for detecting and reporting the CPU throttling activity in Pentium 4, Xeon, and Pentium M processors.

Leave it to the freeware community to take a utility as simple as a CPU monitor and turn it into something complex and powerful. Even though Windows has a built-in CPU monitor, part of the Task Manager, most users demand more information and would rather leave process monitoring to a third party appilcation. No longer is it sufficient to just report what percent of my processor is chugging away at tasks.

With Throttlewatch I'm not only able to monitor my CPU's load but I can also check the processor's voltage, current frequency, temperature, and throttling history. There is a definite benefit for laptop users here because now we can see just what our processors are doing when we unplug our computers. This can help when troubleshooting battery problems or if you just want to figure out if Speedstep is working properly. Throttlewatch can also output a log file in case you want to monitor all these variables while running a benchmark.

The amount of heat a CPU produces varies according to the processing load. In situations of high sustained load (such as performance benchmarks, etc...), a CPU may produce more heat than the cooling mechanism is capable of removing, and reach a high enough internal temperature to trigger throttling.
ThrottleWatch monitors and graphically displays both the CPU load and any throttling that occurs.
When ThrottleWatch is minimized, an icon is added to the system tray area of the Taskbar. The color of the icon changes when throttling is detected.

Types of CPU throttling:
TM1: "Thermal Monitoring 1" throttling is a feature of Pentium 4, P4 Xeon, Celeron ("Northwood" or "Prescott" cores), and Pentium M CPUs. TM1 throttling does not reduce the CPU clock speed - it inserts idle cycles into the instruction pipeline to reduce the processing load on the CPU, which in turn lowers the CPU temperature.

TM2: "Thermal Monitoring 2" throttling is a superset of TM1 and is used on LGA-775 versions of the Pentium 4 and Celeron processors and also on the Pentium M series of processors. TM2 reduces processor temperature by lowering the CPU clock multiplier, and thereby the processor core speed.

The license of this software is Freeware, you can free download and free use this cpu benchmark software.