Rising fuel costs and environmental concerns have made energy conservation a priority for many IT departments. In an effort to help IT managers reduce in-office electrical consumption, DisplayLink recently studied two methods for providing multi-display capabilities and their respective power requirements.

One of the best ways to boost productivity is to add multiple displays to a PC for instantaneous access to information and applications. According to a Microsoft research study, using two or more displays can increase productivity by as much as 50 percent. Researchers at the University of Utah have shown that users of multiple displays make as much as 33 percent fewer mistakes than those working on a single monitor. Along with the additional displays, however, comes increased power consumption and generated heat. In an office setting, this may result in increased building cooling costs and strained local surge protectors.

The DisplayLink study measured the power necessary for a desktop PC to run one to four LCD monitors. Two identically configured systems were used—one equipped with DisplayLink-enabled USB-to-DVI adapters and software and another with dual-DVI discrete graphics cards (the most common type of dedicated multi-display board). Power consumption was measured at the entry of the computer power supply to gauge total system power usage under different system loads.

The study found that adding a display with a USB adapter incurred an average increase of only 4 watts per display, or a 7 percent increase in power consumption. The discrete graphics solution, meanwhile, used considerably more power due to the necessary installation of dedicated hardware inside the computer. When driving a single display, the discrete card used, on average, an additional 34 watts of power, or a 67 percent increase in power consumption—without the benefit of additional displays. When the system was configured to drive four displays (which required the installation of a second card), the power consumption jumped to an average of 117 watts, or an increase of 132 percent compared with the single-display configuration.

Overall, the USB graphics solution used up to 80 percent less power to drive an extra display than a discrete graphics solution. Dennis Crespo, executive vice president of marketing and business development at DisplayLink, said, "We've always said that USB-based networked displays were far more cost-effective and simpler to use than discrete graphics solutions. Now, we've shown they're significantly more energy efficient as well."

Check out our review of DisplayLink's multi-monitor technology. If you're serious about cutting back on electrical usage, whether as part of an initiative to "go green" or simply to lower your electric bills, this is one way to start