Beside the already mentioned Halt/Stop Grant, AMD Athlon 64 knows to reduce the working frequency and the Vcore in order to lower the heat dissipation even more. When this technology is enabled the processor driver manages the CPU clock frequency, by either reducing it or increasing according to the recent information about the CPU workload at that particular moment of time. Of course, if the CPU copes with the work successfully, and its workload is below 100%, its clock frequency can be reduced without affecting the overall system performance. For example, when the system is idle, when you work in office applications, watch video or perform disk defragmentation and the like, the processor doesn’t use all its power. This is exactly the case when the processor driver transfers Athlon 64 to a lower working frequency. As soon as full processor power needs to be involved, for instance in games, for complex calculations or data encoding, the processor clock frequency is returned back to the nominal. This is how Cool’n’Quiet technology actually works.
Now let’s see how the whole thing looks in real life. In common conditions with the minimal CPU workload, the processor driver drops the Athlon 64 3200+ frequency from the nominal 2GHz down to 800MHz.
The processor Vcore in this case drops to 1.3V. As you see, the clock frequency is reduced by lowering the CPU clock multiplier to 4x. This also explains why Athlon 64 are supplied with an unlocked clock frequency multiplier. The CPU keeps working in this mode until its workload exceeds 70%-80%. In particular, we managed to perform disk defragmentation together with MP3 track and MPEG-4 video playback, which the CPU still kept working at 800MHz core clock.
When the workload of the Athlon 64 processor working at 800MHz exceeds the allowed maximum, the CPU is transferred by the processor driver in the following mode:
In this mode the frequency of Athlon 64 3200+ makes 1.8GHz, and the Vcore – 1.4V. This is again achieved by reducing the CPU clock multiplier to 9x this time. And only if the processor workload again appears too high, the driver pushes the CPU back to the nominal settings: 2GHz core clock and 1.5V Vcore.
I believe there is no need ton explain that in workmodes with lower Vcore and working frequency, the Athlon 64 3200+ heat dissipation gets significantly lower. For a better comparison, take a look at the table below showing the heat dissipation of our today’s hero in major work modes:
Typical heat dissipation
Typical heat dissipation during Halt/Stop Grant
This way, the use of Cool’n’Quiet technology allows to significantly reduce the CPU temperature not only when the system is idling, but also when the system is working on the tasks, which do not load the CPU that much. It is also very important that the performance in CPU-hungry applications doesn’t get affected by the Cool’n’Quiet technology at all. As a result, if the cooling solution in your system features a fan with varying rotation speed, the Cool’n’Quiet technology may significantly reduce the noise level of your system. And beside that, we save a lot on the CPU power consumption.