DVFS Dynamic Voltage and Frequency Scaling
Power-management technique that adjusts a CPU/GPU's voltage and clock to match the load — saves battery and keeps temperature down.
Power ≈ capacitance × voltage² × frequency. Halving the voltage saves 4× the power. Linux has the cpufreq governors (performance, powersave, ondemand, schedutil). Phones and laptops rely on aggressive DVFS for battery life. P-states (Performance States) are the ACPI abstraction the OS controls; C-states are idle depths. Big.LITTLE architecture (ARM) takes the idea further with different core types.