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Maximize your PC's energy efficiency

Posted: 04 Jun 2007 ?? ?Print Version ?Bookmark and Share

Keywords:PC energy efficiency? business PCs? Energy Star 4.0?

By Jon Carter
Hewlett Packard

PC manufacturers continue to explore and develop energy-efficient technologies by providing customers with no-compromise, energy-efficient, environmentally friendly desktops. As environmental agencies adopt and promote energy-efficient regulations, it is even more important for businesses to consider deploying computers engineered with power efficient features.

When a PC can deliver maximum energy savings, along with enhanced system reliability and a longer equipment lifecycle, this can lower the overall total cost of technology ownership. This article provides five criteria for choosing business PCs that can lower energy consumption, reduce PC noise and increase a PC's overall reliability!all of which can increase a system's lifecycle and help businesses achieve an overall better return on their IT investment.

Step 1: Seek power management tech
Choose a system that has power management technology and enable this technology on your systems.

Computer processor manufacturers are integrating the ability to manage power use directly into their latest processors. Enhanced Intel SpeedStep Technology and AMD Cool 'n' Quiet Technology both include features that work with the BIOS and OS to lower power consumption.

Business PCs with these types of processors use less power when software activity does not require the full capabilities of the processor. Along with being more environmentally friendly, reduced power consumption results in reduced heat production. Less heat means lower fan speed requirements, thus providing quieter, more efficient computers. This technology is also especially useful for notebook computers, as reduced power consumption leads to increased battery life.

Step 2: Eye configurable BIOS
Choose a system with a BIOS that offers a wide range of configurable power management options. Select PCs offer five system states that can be configured to provide increased levels of power efficiency.

PCs with configurable BIOS allow the user or IT manager to balance the thermal requirements and the acoustic levels of the computer to ensure that the computer performs optimally in any environment. Configurable BIOS enables users to control the computer airflow in their computers by adjusting the fan speed to be maximized for environments where thermal concerns are a priority, or minimized for acoustically sensitive environments.

The Advanced Configuration and Power Interface (ACPI) specifications set the technology industry's standard for energy and power system states. ACPI defines several system states described below:

  • S1: Standby state resulting in the processor being halted, but context is not lost. All other devices remain at the normal power state. This state offers the fastest wake-up time and the lowest power savings.

  • S3: Standby state known as Suspend to RAM. All devices in the system are powered down, except for computer memory. Recovery is almost instant (approximately 2-3s) and power consumption is very low (typically
  • S4: This state is referred to as Hibernation. The computer's memory content is saved to the hard drive, then most power is removed from the system.

  • S5: This state is often referred to as Soft Off. The computer is off. This state offers the slowest wake-up time and the greatest power savings (typically

To understand the potential cost savings of user configurable BIOS, consider an example using the power difference between configuring systems to standby in an S3 Suspend to RAM state (system power dissipation is under 5W) vs. simply allowing a system to idle (system power dissipation is approximately 90W in a mainstream Intel Pentium 4 configuration). In this scenario, assume users simply let their system idle when they are not working!which is typical as many users do not power off their systems at the end of the work day due to the inconvenience of waiting for the system to power up and complete the initial loading of their OS the next morning.

Calculate the cost savings during after-work hours (5p.m. to 8a.m.) in an enterprise with 1,000 systems. Saving approximately 80W for 15hrs/day at an average energy cost of 12 cents/kWh, for an average work year of 250 days, could result in a cost savings of $36,000.00 annually for an installation of 1,000 systems.

Step 3: Select power-efficient processors
Choose a system processor that provides the maximum level of power efficiency.

Many watt classifications of processors exist, but the most common available today are 95W, 65W and 35W processors. While 35W processors achieve the maximum in power savings, 65W and 95W devices provide mainstream power savings.

Selecting an AMD configuration with an X2 3800+ 35W processor configuration may yield the best energy efficiency vs. other AMD wattage classifications. AMD 35W processors?at idle, average and peak?reduce energy consumption up to 5 percent, 20 percent and 15 percent, respectively vs. AMD 65W processors in a similar configuration.

Likewise, selecting an Intel system with a Core 2 Duo 65W processor configuration can yield the best energy efficiency. The 65W processors?at idle, average and peak?reduce energy consumption up to 11 percent, 36 percent and 26 percent, respectively vs. Intel 95W processors with similar configurations.

These types of processors keep power requirements to a minimum. At one time, increased performance often meant higher power consumption and more noise. With the development of power efficient processors from AMD and Intel, performance is treated as "on-demand," which helps reduce processor heat. On-demand processor frequency and voltage switching help decrease power and fan speed?resulting in a cooler PC and a quieter work environment.

Step 4: Aim for 80% efficiency
Choose a system configuration with an 80 percent efficient power supply. These power supplies can reduce energy consumption, provide RMS and peak AC current reduction.

In a typical commercial building, as much as 10 to 15 percent of the overall energy bill is driven by energy consumption of the power supplies used in most business technology. Newly available 80 percent efficient power supplies are 33 percent more efficient than current power supplies because they reduce the power drawn in waste heat that is dispersed into the environment. This is according to 80 PLUS, an electric utility-funded incentive program focused on integrating more energy-efficient power supplies into desktop computers and servers. HP was the first major PC manufacturer to support the program, and recently made its first PCs with 80 percent efficient power supplies available to the public.

Businesses choosing PCs configured to meet the upcoming Energy Star 4.0 guidelines may not only conserve energy due to required 80 percent efficient power supplies, but can also benefit from increased system reliability, reduced system maintenance costs, as well as decreased air conditioning costs!all due to less heat generation, which can also greatly extend the life of the system.

Another important benefit of the 80 percent efficient power supply is its 0.9 active power factor correction (PFC), which means that 90 percent of the system's apparent power is actually transferred to available real power. Power supplies that aren't power factor corrected tend to cause unpleasant variations in AC voltage that can affect or even damage other equipment on the same circuit. Active power factor correction in the power supply causes the RMS input current to drop by nearly 50 percent, and the peak AC input current by over 75 percent compared with non-power factor corrected power supplies.

Systems with 80 percent efficient power supplies are of particular importance since the U.S. Environmental Protection Agency revised its Energy Star certification requirements for hardware. Effective July 20, 2007, the new guidelines require computers to incorporate "80 percent efficient" power supplies to meet the new, more stringent Energy Star 4.0 criteria.

Most importantly, 80 percent efficient power supplies can reduce the need for system maintenance by improving system reliability, extending equipment life, and minimizing fan noise; all resulting in lower total cost of ownership.

Step 5: Use LCDs over tubes
Replace CRT monitors with LCD technology as it provides up to 70 percent power savings and up to twice the lifespan of CRT monitors.

Replacing CRT technology with TFT or "flat panel" technology can provide substantial power savings. For example, a floor with 100 workstations would require energy consumption of 9,000W/hr if equipped with CRTs, vs. only 1,700W/hr when equipped with comparable 15-inch TFT monitors. In addition to the benefits TFTs offer in these areas, their smaller size requires less desk and office space to maximize office space. The smaller footprint can also help reduce general overhead costs associated with office furniture, lighting and rent.

With the rising cost of energy resources, there's a lot at stake when it comes to technology's far-reaching influence on the environment. As PC manufacturers recognize their indirect relevance to exacting change by incorporating energy-saving technologies into their products, businesses and their customers!as well as the general population!will benefit from these environmentally-conscious products and the extensive savings they provide.

About the author
Jon Carter
is the worldwide product manager of Hewlett Packard.

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