New-Tech Europe | September 2016 | Digital Edition

Figure 2. PMBus-compatible converters allow digital optimization on the fly to optimize energy efficiency.

Multicore activation on demand provides a means of activating or powering down individual cores of a multicore processor in response to changes in load. Clearly, de- activating unused cores at times of low processing load can help to gain valuable energy savings. Adaptive Techniques and Potential Savings These are the first adaptive features to be implemented, as power supply developers begin introducing software-defined power architectures. Many additional, powerful techniques are expected to emerge, assisted by the arrival in the market of PMBus-

fault management, sequencing, ramp- up, and tracking. As system designers are developing more effective ways to exploit the controllability PMBus brings, power architectures are becoming software defined and respond in real-time to optimize efficiency. Some of today’s most powerful techniques for optimizing efficiency include Dynamic Bus Voltage (DBV) optimization, Adaptive Voltage Scaling (AVS), and multicore activation on demand. DBV provides a means of adjusting the intermediate bus voltage dynamically to suit prevailing load conditions. At higher levels of server-power demand, PMBus instructions can command a

higher output voltage from the IBC in order to reduce the output current and hence minimize distribution losses. AVS is a technique used by leading high-performance microprocessors to optimize both the supply voltage and clock frequency to ensure processing demands are always satisfied with the lowest possible power consumption. AVS also enables automatic compensation for the effects of silicon process variations and changes in operating temperature. To support AVS, the PMBus specification has recently been revised to define the AVSBus, which allows a POL converter to respond to AVS requests from an attached processor.

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