It is especially interesting to check out the system power consumption in idle mode when there is no workload in place because contemporary computer systems are in fact in this mode for quite a long time. For example, while you are reading this article the system is most likely in idle mode unless there are flash banners on the screen. Most of the time a computer system is idle even in those applications, where things happen only in response to user’s actions. A typical example of an application like that would be office tasks, for instance. In other words, even though system power consumption in idle mode doesn’t affect the cooling system or power supply requirements, but it certainly plays its role in the amount of your monthly power bill.
If we put CPU overclocking aside, then in terms of energy-efficiency we will see a pretty transparent dependence in idle mode. LGA775 and LGA1156 systems consume the least power of all. AMD platforms require a bit more power, while the system with an expensive LGA1366 processor needs over 1.5 times more power for its idle mode needs. Overall, the same situation repeats also during overclocking. Only quad-core processors on Nehalem microarchitecture, Core i7-950 and Core i7-860, behave differently here. The idle mode power consumption of platforms equipped with these CPUs increases during overclocking a bit more than in all other cases.
The workload created during image editing in Photoshop is interesting for power consumption tests because of its diversity. Filters and operations used for color photo retouching are optimized for multi-core processors in totally different ways and load the memory bus with different intensity. Therefore, the utilization of computational cores and overall system resources is extremely uneven in this graphics editor. As a result, processor cores would go in and out of different power-saving modes, and Turbo Boost technology would constantly work in corresponding Intel processors.
Power consumption remains relatively low under workload of this kind. Even overclocked systems with high-end processors never get beyond 200 W. However, the best result in terms of power-saving belongs to a Clarkdale based platform. No wonder, since these processors are manufactured with the newest 32 nm process. Although, you shouldn’t forget that dual-core processors cannot outperform quad-core ones. Therefore, you should definitely take into account not only Core i3-540, but also Core 2 Quad that can boast low power consumption during overclocking even despite having four cores onboard.