Energy-Efficient Computing Options

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Motherboard And Memory

The platform is more difficult to analyze than the processor, as the power requirements depend on a larger number of factors. First and foremost there is the chipset, which mostly determines the capabilities and feature-sets of a modern PC. In the AMD arena, there are several Nvidia nForce 500 series chipsets, which offer great features paired with high-performance. nForce 600 only works for the dual-socket FX-70 platform. AMD itself offers the AMD 690 chipset and there are several other chipset options that SiS and VIA offer. The latter, however, aren't competitive in terms of features and overclockability, but they might still provide a good bang for the buck as long as you don't have specific requirements regarding AMD/ATI or Nvidia dual-graphics support. On the Intel side, there is an nForce 600 offering again, which supports Nvidia SLI dual and quad graphics, and Intel's 965 and 3 series chipsets (P35, G33). Again, SiS and VIA have offerings as well, but these cater to business and low-budget customers.

Platforms for AMD processors typically consume a bit less energy, as the Northbridge components do not include the dual-channel memory controller that Intel core logic products offer. However, the main differentiator can found in the number of features supported by the chipset, and the positioning of the motherboard product. Enthusiast chipsets for gamers and workstation users today offer a plethora of PCI Express lanes to power dual x16 PCI Express graphics, multiple USB 2.0 and SATA ports. However, all these serial links consume energy, which means that the more you have, the higher the power requirements tend to be.

In addition, the electrical specifications have an impact on power requirements; voltage regulators with multiple phases to share the workload provide more stable power supply and higher currents for top-of-the-line processors. However, each regulator that is added to the array reduces the overall efficiency of the circuit, hence increases the overall power requirement of the motherboard. If you want to keep the power requirement of a motherboard low, you'll have to stick with three or four phases, and make sure that the board only comes with the on-board components you actually need.

The only option to further reduce power consumption is a MoDT solution, which involves the use of a mobile chipset on a desktop motherboard. AOpen was aggressive with its MoDT solutions at the beginning of last year, offering a 975X motherboard that supported a Core Duo processor on socket 479M (i975Xa, YDG). These low-power platforms perform very much like their desktop counterparts with the difference being that they sometimes lack overclocking options and don't necessarily support the latest memory speeds, either. But again, such motherboards come in small quantities, which makes them expensive and rather unattractive, as the power savings are less significant than what you can save by choosing a processor and a graphics card.

Let's not forget the memory, either; each generation of DDR memory requires less energy than the previous one. DDR2 requires less power than DDR, and DDR2 is more efficient than DDR3 - if compared at the same clock speeds. The main reason is the advanced manufacturing process, which allows for the reduction of the supply voltage from 2.5 V with DDR to 1.8 V with DDR2 and 1.5 V with DDR3 memory. This alone entails significant savings, although the power consumption of two DDR2 memory modules is somewhere between 5 and 15 W - depending on the memory density, clock speed and memory voltage. Enthusiast memory modules, which are designed to break speed records, will run at increased voltage levels and will clearly increases power consumption by a few Watts.