System Power Consumption

The four result values are as following:

• AMD Cool'n'Quiet / Intel SpeedStep: Windows 7 with Aero off, sitting at the desktop (1920x1080 32-bit) all windows closed, drivers installed. Processors have their power saving technology enabled, left in idle until power draw is stable.
• Idle: Windows 7 with Aero off, sitting at the desktop (1920x1080 32-bit) all windows closed, drivers installed. Processors have their power saving technology disabled, left in idle until power draw is stable.
• Load: Prime95 is used to increase load on all available cores and measurements are taken when power draw is stable.

When first released, C'n'C and Speed Step were not so well accepted by desktop users because many bugs in performance and overclocking stability appeared when activated. But since then those technologies have greatly evolved. Today it is almost unthinkable to turn off Speed Step/C1E with Intel Core ix processors because you would automatically loose Turbo Boost benefits, and there is an increasing number of enthusiast who overclock their processors and then push for additional MHz using Turbo Boost. So will our measurements of Idle and Load CPU states shift to those with power management features turned ON. Today idle power usage can have a noticeable impact on your electricity bill if keep your computer on most of the day, and most people do just that. So a bad implementation of power management technologies is and will be considered a product flaw.

Idle power usage data graphs without C'n'C/SpeedStep will be kept for older models of processors, as a comparison to how much energy and heat is saved by turning these features on.

As for Core i5 661 it has excellent power usage numbers when loaded, providing in most cases Q9400 or better performance and saving ~20W at the same. But idle power consumption can and would be greatly improved by implementing some on/off switch on the IGP part of the processor when used in P55 motherboards. Although not used or connected to anything, the IGP inside Clarkdale just sits there idling at very high 900 MHz clock, hence Core i5 661 has bigger idle power consumption than a 45 nm quad core Core i5 750. Not by much but still...