HP has tweaked three of its PCs to meet a new environmental standard.

The company has modified its HP Compaq dc5700, dc5750 and dc7700 by switching the machines into sleep modes sooner than current models to qualify for the recently-introduced US Environmental Protection Agency's Energy Star 4.0 label. In addition, HP has started using an 80 percent efficient power supply instead of the current range of 65 percent to 75 percent efficiency, said Nancy Bowman, HP's commercial desktop product marketing manager for North America.

HP hopes the revamped computers will appeal to institutional IT managers who face a corporate requirement to meet efficiency standards, Bowman said. There are now about 80 desktop models listed in the EPA's Electronic Product Environmental Assessment Tool website listing of "green" desktops that avoid toxic substances, are easily recycled and are energy efficient. But most of those desktops meet the EPA's current, lower standard, Energy Star 3.0.

In October, the agency said it would upgrade that standard for the first time since 2000 because 98 percent of all products in the marketplace met its requirements. In an effort to give the Energy Star badge more elite status, regulators raised the bar so it would include only the top 25 percent most efficient desktops, notebooks, tablets, workstations, low-end servers, and game consoles. The new standard takes effect July 20 and upgrades to an even tougher, Tier 2 standard in 2009.

HP will charge $959 for a dc7700 with Intel Core 2 Duo processor, 80B hard drive and Windows XP Pro, $899 for the dc5700 with similar specs, or $609 for a version with AMD's Athlon chip.