While the 2560x1600 scores are the only ones that really matter in ultra-high-end graphics solutions, an average of all test settings will help us more accurately judge the overall efficiency of each graphics solution. Efficiency is, after all, a ratio of work done to energy consumed.
The single GTX 280 took last place in performance and first place in power conservation. We used it as the basis for comparing the energy-to-work ratio of each graphics solution.
Surprisingly, the single-unit, dual-GPU GTX 295 provides the most performance per watt. The once-green AMD looks a peculiar shade of pink as its Radeon HD 4870 X2's efficiency is particularly embarrassing in CrossFireX mode.