Cool'n'Quiet 2.0 In Detail
The core voltage regulation for the CPU has seen a few changes in version2.0 of the Cool'n'Quiet technology. Until now, the voltage ID (VID) on the Athlon 64 processor was transmitted to the BIOS and the voltage regulation modules using several parallel data lines. The drawback to this technique is that the range of values that can be set is rather small.
Our Phenom operated at 1.232 Volts
Beginning with the Phenom, AMD will use a serial VID protocol . The serial method transmits voltage IDs using a 7 bit code, allowing the voltage to be set in 12.5 mV steps. As a result, a wider range of voltage options becomes available, which in turn means AMD can sell its processors with a much more finely-tuned core voltage, reducing the thermal dissipation of many models. Overclockers, meanwhile, also benefit from the new technique, since they can also select the voltage much more precisely, saving a few watts of power consumption even at high clock speeds.
The BIOS offers core voltage options
If the processor's full performance isn't needed, it reduces its clock speed using Cool'n'Quiet. For each of the P-states with their individual clock speeds, the core voltage is also reduced in order to cut down on energy consumption. In version 2.0 of Cool'n'Quiet, the Phenom processor can effect changes to the core voltage without using the STPCLK or STOPGRANT protocols . Since the CPU no longer has to completely stop its frequency for these changes, it doesn't lose any CPU time, making the processor a little faster. Since the CPU operates in the gigahertz range, the savings only amount to a few nanoseconds. According to AMD; this technology is meant to prevent hiccups in audio and video playback due to Cool'n'Quiet.