RightMark CPU Clock Utility v2.0
 

RightMark CPU Clock Utility (RMClock) is a small GUI application designed for real-time CPU frequency, throttling and load level monitoring and on-the-fly adjustment of the CPU performance level of the supported CPUs via processor's power management model-specific registers (MSRs). In automatic management mode it continuously monitors the CPU usage level and dynamically adjusts the CPU frequency, throttle and/or voltage level as needed.

http://cpu.rightmark.org/