Note that our power consumption results include not just the processor but the entire system, in practical terms this is a better measurement for comparing the different platforms and CPUs we tested.
The new Intel LGA1156 processors are in a league of their own when it comes to idle consumption. The most powerful processor we tested also used the least amount of power at idle, with a system consumption of just 68 watts. The Core i5 650 and Core i3 540 processors used slightly more power, likely due to the onboard GPU. That said, both still consumed less than 80 watts of power, making them more efficient than the Core 2 Duo E7500 which was the slowest processor tested.
The Phenom II X4 965 was particularly hungry at idle, consuming 164 watts of power, which is roughly 2.5x more than the Core i5 750. Overall the idle consumption levels of the AMD processors were comparable to those of previous generation Intel products.
When measuring load or stress performance with Prime95 we see a different picture. The Core i5 750 now consumes considerably more power than the Core i5 650 and Core i3 540 processors, which are the most power conscious when under load. The Core 2 Quad Q9400 is now the most power hungry processor, followed by the Phenom II X4 965.