Intel® Core™ Duo processor technology closely interacts with other components on the platform. One such component is the Voltage Regulator (VR). VR power losses at low CPU utilization may get as high as the CPU power. The losses of the VR are due to the need to deliver high current at quick respond times. Intel® Core™ Duo processors implemented a feedback mechanism to the VR. The CPU tracks its activity at any time. If utilization goes down, the CPU communicates a signal to the VR, allowing it to switch to a lower power consumption. A lower power state can be either a reduced number of phases or asynchronous operation. The communication is done using the voltage ID lines and PSI signal as described in Figure 10.

Figure 10: Voltage regulator interface
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The CPU has internal knowledge of the activity demand and it communicates a request to go to higher power early enough for the VR to get ready for the increased demand.

Another power optimization is load line control. At low CPU activities, the voltage drop on the load line is smaller resulting in higher voltage and power to the CPU. At low workloads, the CPU reduces the voltage request, and early enough, before power consumption increases, a voltage increase request is sent to the VR.

Using utilization knowledge, available in the CPU, Intel® Core™ Duo technology made it possible to reduce platform power, increase battery life, and improve form factor ergonomics.