Laptop Batteries That Last All Day?

If you aren't into photo editing or ripping music, and your laptop is less than two years old, your machine may not strike you as too slow. But even if you have yet to plunge into graphics, demands on your system are rising, with pictures in e-mail, video on Web sites, and programs that monitor the state of your PC. Intel (INTC ) has no choice but to make faster hardware.

The company recognized several years ago that its strategy of boosting performance by making mobile chips run faster was taking too great a toll on battery life. The answer, first offered in 2003, was the Pentium M (branded as Centrino when coupled with an Intel Wi-Fi network adapter). The Pentium M had a slower clock speed, or megahertz rating, than the chip it replaced. But it greatly enhanced performance in other ways, such as fetching instructions and data more efficiently.

The newest version of the Pentium M, code-named Sonoma, takes this a step further. Initial versions of the processor keep the maximum clock speed essentially unchanged, at a little more than 2 gigahertz. Instead, performance is boosted by dramatically increasing the speed at which the processor communicates with other components. There's a 33% bump in the speed at which data move between processor and memory. And a technology called PCI Express allows video to be pumped to graphics adapters at much higher speeds. The result is a considerable narrowing of the gap between laptop and desktop performance. This does come at some cost in battery life, however, with most manufacturers reporting a decline of 20 to 30 minutes of running time on similar models.

THE NEWEST PENTIUM M CHIPS ARE SHOWING up in a broad range of laptops. I had a chance to try three of them, and in general, I'm impressed. The Gateway (GTW ) M460E is a low-end Sonoma consumer notebook that crams a lot of value into a $999 package, including a 15-in. display. Other models come with a 15.4-in. wide-screen display. At about 6 lb., you wouldn't want to carry the M460 every day, but it's reasonably mobile.

The IBM (IBM ) ThinkPad T43, starting at about $1,500, is the Sonoma version of a thin, light corporate workhorse. It's just an inch thick, weighs around 5 lb., and comes with a 14.1-in. or 15-in. display.

The Dell (DELL ) Latitude D410, starting at $1,677, is the lightest of this trio and has the longest battery life. Aimed at mobile executives, it weighs just 3.8 lb., and the battery lasts about seven hours. But you have to make do with a 12.1-in. display and no built-in DVD drive. And to get those extra hours, the D410 uses a much higher-capacity battery than its predecessor.

Sonoma processors will power most notebooks this year. The main challenge will come this summer from an Advanced Micro Devices (AMD ) chip called Turion, designed to match Pentium M's efficiency. Don't expect much new in notebook designs, though -- manufacturers usually make big changes only when Intel introduces a new processor.

The next big wave of change will come in 2006, when Intel breaks away from the decade-old mobile Pentium tradition. Its next chip, code-named Yonah, will have two processors in a single package. That should be a big advantage, since two relatively slow processors can perform better while consuming less power than can a single, faster one. Software can further boost efficiency by using just one processor for some tasks.

The transition to these so-called dual-core chips should be fairly slow because a version of Windows that takes full advantage of the technology isn't expected until late 2006. But it should be a big deal. Centrino led to a generation of speedy, lightweight notebooks that eliminated the network cable and allowed a long time away from the electrical outlet. If Yonah delivers, we'll finally have notebooks that run all day on a single battery charge.

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By Stephen H. Wildstrom

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