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Notebooks with desktop processors may promise better performance than those with notebook chips, but the added processing power means nothing if the desktop chip overheats the laptop and causes it to malfunction.

Problems with such a machine, Toshiba's Satellite 5005 series notebook, has spawned a class action lawsuit, a step that might cause PC vendors to rethink how they design and market such machines.

Last month, Toshiba America was hit with a class action lawsuit filed by users who allege Toshiba was aware its Satellite 5005 notebooks contained a design flaw that caused them to overheat and shutdown when processing large applications.

Many vendors, including Dell Computer, Hewlett-Packard, and Gateway, have also released notebooks powered by desktop processors, promising the power of a desktop computer with the portability of a laptop.

Heated Discussion

However, Intel, Advanced Micro Devices, and Transmeta make processors designed specifically for notebook computers for a reason, analysts say.

Desktop processors run at higher voltages than mobile ones, and therefore need to dissipate more heat than mobile processors. This isn't a big deal in a desktop chassis with space for elaborate heatsinks and cooling fans, says Kevin Krewell, senior editor of The Microprocessor Report and general manager of market research company MDR. But a notebook computer doesn't have this extra space, so more heat is retained by the machine, he says.

Notebook chips are designed to operate at lower wattages to avoid crossing the heat threshold that forces the machine to shut down, but desktop chip developers aren't as concerned with that constraint. This was the problem encountered by some Satellite 5005 users, who found their notebooks shutting off in the middle of processing graphics presentations or playing graphics-intensive games, or running much slower than advertised processor speeds during normal use.

This is a fundamental problem with using desktop processors in notebooks, says Krewell. A vendor can design around these problems by adding heat shields or using an advanced heatsink, but those remedies add price and weight to notebooks.

"You can do a better job of managing a desktop part in a notebook, but it's just not optimal," he says.

Saving Time and Money

Notebook vendors have fallen in love with desktop processors because mobile processors are far more expensive than desktop chips running at the same clock speed. However, there's a value in the mobile chips, says Krewell.

Mobile chips are designed to reduce their processing speed for applications that don't require the full strength of the chip, preventing excessive heat by lowering overall power consumption. But they still operate at their advertised clock speed when crunching large applications, he says. Intel's SpeedStep technology is an example of this, lowering power consumption even between keystrokes, and kicking in extra power when needed.

The recent spate of notebooks powered by desktops has been largely targeted at consumers, as IT managers aren't fooled by promises of increased power without mobility or power consumption tradeoffs, says Alan Promisel, research analyst at IDC.

"Businesses want notebooks that can deliver true mobile enterprises," he says, and they're also looking for value in their infrastructure. Consumers, especially those interested in gaming, often are looking for the highest performance they can afford, and vendors have been able to deliver that performance at a lower cost through the use of desktop processors, he says.

Smart Shoppers

Both analysts feel that vendors will continue to sell notebooks with desktop processors, but consumers are starting to realize that clock speed isn't necessarily the best measure of chip performance. The introduction of Intel's Banias chip in the first quarter of 2003 may help to reinforce that view, since it reportedly will be released at clock speeds below Intel's current Mobile Pentium 4 chips.

Notebooks are the only bright spot in the PC industry right now, growing at a reasonable clip while the desktop market stagnates. The rush to get low-cost notebooks out on the market might have caused some vendors to overlook the problems associated with using desktop processors in laptops, says Krewell.

"There's just a stampede to get a piece of that pie, and it's the customer that's getting screwed," he says.

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