Power Consumption Measurements
We did not measure the power draw for the nForce 680i platform with DDR2-1066 memory, since this memory speed hasn't been specified by JEDEC (and probably never will be). 266 MHz DDR2 speed for DDR2-1066 requires a voltage increase to 2.2 V and more, so you can be sure that this setup will consume even a bit more than at DDR2-800 speed. Of course this applies to all platforms.
Clearly, the Intel chipsets are more energy-efficient than Nvidia's nForce 680i SLI, although the difference is small. The 680i SLI consumes about 5% more power when idle and roughly 14% more if power management options are enabled (SpeedStep technology). The additional power draw under full CPU load is about 12 to 14% higher (compared to the 975X and P965). Nvidia says that nForce 680i SLI was designed for overclocking, which is the most logical explanation for the increased power draw: slight voltage tweaks will ensure proper overclocking stability, while introducing somewhat higher power requirements.