Notebook PC users who upgrade to Vista may have to disable some of the new operating system's flashy graphics features to avoid seeing a decrease in battery life.
The drop will come from the extra power needed to run the high-end processors, graphics cards and memory capacity required to support Vista. Microsoft has designed the new OS to deliver novel visual effects such as translucent "Aero" windows on the desktop interface.
PC and hardware vendors see Vista as a windfall because it requires faster, more powerful computers. But the extra power comes at a price. "Vista demands more compute resources for a given application than XP does. So you need a heavier battery or you will have shorter battery life because of the greater demand for watts," said Phil Hester, chief technology officer of AMD.
Dell also said that Vista's appetite for computing resources will increase its draw on battery power.
"If Vista is run in full Aero mode, with none of the Vista-provided power management settings turned on, it is likely to demand more power, and have an impact on battery life," said Dell spokesman Ira Williams. "That said, if you run Vista in battery-optimised mode (using non-3D interface), we would not expect the battery life to be significantly different from XP in that scenario."
A Microsoft spokeswoman confirmed that Vista will allow users to disable or tune down graphics as part of a power management package meant to keep Vista battery life on par with Windows XP. But she said the graphics have a smaller effect on battery life than other hardware in the PC.
"Although it is true that the Windows Vista Aero theme and components can use more resources than previous versions of Windows, the relative impact to battery life is minimal," said Microsoft spokeswoman Kristin Farmer.
"Microsoft is working with device manufacturers to ensure their device drivers are optimally tuned for performance and power savings. We recognise that battery life isn’t just a Microsoft issue and involves our partner’s decisions as well."
Microsoft said that it had designed Vista to allow notebook PC users to save battery power by turning down the screen brightness, volume, wireless networking and other attributes. Vista also has a power-conservation mode called sleep, similar to the "standby" and "hibernate" modes in previous versions of Windows.
A spokesman for Gateway agreed that Microsoft's power conservation steps can make a difference in compensating for the extra hardware.
"We've done extensive testing and we haven't seen [shortened battery life]," said Gateway spokeswoman Kelly Odle. "While it is true that Vista has higher system requirements than XP, it also has more sophisticated mechanisms to allow for power savings."
Still, users who need to preserve battery life will face a trade-off in giving up some of the most impressive new features, said Richard Shim, an analyst with IDC.
"It's a common criticism that any new Windows OS will have a toll on battery life," Shim said. "If you look back at XP and Windows 98, it took a while for folks to learn how to optimise the hardware. And as the PC market continues to rely on notebooks to drive shipment growth, this will be a big thing."
Notebook PC users can manage power by choosing to reduce the time it takes their processors and hard drives to switch into hibernation mode, turn off their sound and Wi-Fi, avoid running 10 applications at once, and turn down the brightness of their screens - the one component that consumes more battery power than any other computer part, Shim said.
Some hardware makers are also helping out, as they are striving to squeeze an extra 2 percent to 5 percent efficiency out of the chipset, graphics component and BIOS, Shim said. However, they face a limited power budget, since battery technology has not improved significantly in recent years, and PC vendors are unlikely to specify a larger cell, since that would add to the PC's size, weight and cost.
"That can add up to savings, but it's not enough to overcome the fact that Vista is not battery-friendly," Shim said.