As expected the lower TDP of the 32nm Core i5 661 translates into further power savings compared to the already amazing levels we saw from the Core i5 750 a few months ago.
Our power consumption test takes into consideration the complete platform running the same third-party components (graphics, etc.). The built-in graphics from the Core i5 661 were turned off so we could make a straight comparison against the rest of the systems using a GeForce GTX 285 graphics card.
All in all, the entire Core i5 661 configuration used just 88 watts at idle and 142 watts under load. This made the Core i5 661 ~20% more efficient than the Core i5 750 when under load, and 35% more efficient than the Phenom II X4 945.