Definition
Dynamic voltage and frequency scaling (DVFS) is the practice of adjusting a chip's supply voltage and clock frequency together to balance performance against power. It exploits the physics of CMOS: dynamic power rises with the square of voltage and linearly with frequency, so lowering both at once cuts power far faster than it cuts work done. DVFS is the formal name for the voltage/frequency tuning that mining firmware exposes as power modes.
The voltage-frequency relationship
A faster clock demands a higher supply voltage so transistors can switch in time; a slower clock can run safely at a lower voltage. Because power scales roughly as voltage-squared times frequency, dropping frequency a little lets you drop voltage too, for a multiplied saving in watts. This is exactly why an undervolted, slightly down-clocked miner can hit a better efficiency (J/TH) than the same chip at stock.
DVFS in mining firmware
Custom firmware power profiles are applied DVFS: each preset is a coordinated voltage and frequency pair characterized for a given chip family. Pushing frequency up for more hashrate without enough voltage causes hardware errors; raising voltage without need just wastes power as heat. Good autotuning searches the voltage-frequency surface to find the most efficient stable point for each individual chip, since silicon quality varies part to part.
The voltage half of the trade-off is delivered by the voltage domain, and the frequency half is synthesized by the phase-locked loop.
In Simple Terms
Dynamic voltage and frequency scaling (DVFS) is the practice of adjusting a chip’s supply voltage and clock frequency together to balance performance against power. It…