The Performance-Per-Watt, Efficiency Of Intel/AMD/NVIDIA GPUs On Open-Source Drivers
The most power hungry graphics cards of the GPUs tested on the open-source drivers were the Radeon HD 6950 and Radeon HD 4890 graphics cards. The NVIDIA graphics cards were going through less power due to their lack of re-clocking support, thus were running at their lower boot frequencies (and voltages) rather than their optimally-rated performance levels.