Higher clock rates make CPUs consume more power. However, as the manufacturing process is being polished off, the thermal and electrical parameters of CPU dies improve. These two trends usually counterweigh each other, so newer CPUs working at higher clock rates do not differ much from their predecessors in terms of power consumption.
The graphs below show the full power draw of the computer (without the monitor) measured after the power supply. It is the total of the power consumption of all the system components. The PSU's efficiency is not taken into account. The CPUs are loaded by running the 64-bit LinX 0.6.3 utility. We enabled all the power-saving technologies for a correct measurement of the computer's power draw in idle mode: C1E, AMD Cool'n'Quiet and Enhanced Intel SpeedStep.
AMD processors are still less energy-efficient than their direct opponents from Intel. The Phenom II X4 970 is especially disappointing as its system consumed more power than the Core i7-860 based platform under load. AMD promises certain improvements for off-the-shelf samples of these new CPUs in terms of power consumption and heat dissipation. This can hardly change the picture dramatically, but the Phenom II X4 970 is likely to become more economical than the six-core Phenom II X6 1075T.
The new quad- and dual-core Phenom II processors do not differ much from the Core i5 and i3 series in terms of power consumption when idle. It means that modern power-saving technologies are so effective that the CPU is not the main consumer in an idle computer. Other components such as the graphics card, disk drives, mainboard and memory consume much more in this mode. Unfortunately, the Phenom II X6 1075T is not so economical when idle: although it has Cool’n’Quiet technology, it does not lower its voltage as low as its Deneb-core cousins do.