Résumé
Dynamic frequency scaling (also known as CPU throttling) is a power management technique in computer architecture whereby the frequency of a microprocessor can be automatically adjusted "on the fly" depending on the actual needs, to conserve power and reduce the amount of heat generated by the chip. Dynamic frequency scaling helps preserve battery on mobile devices and decrease cooling cost and noise on quiet computing settings, or can be useful as a security measure for overheated systems (e.g. after poor overclocking). Dynamic frequency scaling almost always appear in conjunction with dynamic voltage scaling, since higher frequencies require higher supply voltages for the digital circuit to yield correct results. The combined topic is known as dynamic voltage and frequency scaling (DVFS). Processor throttling is also known as "automatic underclocking". Automatic overclocking (boosting) is also technically a form of dynamic frequency scaling, but it's relatively new and usually not discussed with throttling. Processor power dissipation#Sources The dynamic power (switching power) dissipated by a chip is C·V2·A·f, where C is the capacitance being switched per clock cycle, V is voltage, A is the Activity Factor indicating the average number of switching events per clock cycle by the transistors in the chip (as a unitless quantity) and f is the clock frequency. Voltage is therefore the main determinant of power usage and heating. The voltage required for stable operation is determined by the frequency at which the circuit is clocked, and can be reduced if the frequency is also reduced. Dynamic power alone does not account for the total power of the chip, however, as there is also static power, which is primarily because of various leakage currents. Due to static power consumption and asymptotic execution time it has been shown that the energy consumption of software shows convex energy behavior, i.e., there exists an optimal CPU frequency at which energy consumption is minimized.
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Un appareil électronique de faible puissance est un appareil électronique qui a été conçu pour utiliser peu de puissance électrique, par exemple un ultraportable. Montre Les premières tentatives de réduction de la quantité d'énergie requise par un dispositif électronique ont été liées au développement de la montre-bracelet. Les montres électroniques ont besoin d'électricité comme source d'énergie, et certains mouvements mécaniques et mouvements électromécaniques hybrides ont également besoin d'électricité.
Underclocking
L'underclocking (mot anglais), parfois francisé en sous-fréquençage ou sous-cadencement, d'un processeur, consiste à diminuer sa fréquence de fonctionnement, par opposition à l'overclocking. Cette technique permet de diminuer la consommation électrique et donc la production de chaleur. Cela permet aussi de diminuer la tension d'alimentation en dessous de valeurs minimales conseillées par le fabricant du CPU tout en restant stable.
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