yeppers, it is called EIST

or Enhanced Intel Speedstep Technology. The ACPI interface causes the CPU to throttle for power and heat saving purposes whenever there is no load on it- going back to the lowest supported multiplier by the architecture, in the case of the P4 "Prescott", that was 14x. Under load, the CPU would ramp up the voltage first and then follow with a multiplier increase up to the rated maximum of the particular CPU.