Mobile CPU buyer's guide

Buying a new laptop? Not sure which processor to get? We can help.

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Low-power mobile processors

Low-power processors are just what they sound like -- CPUs that are specially designed to sip as little power as possible. They are typically less powerful than standard CPUs, with slower clock speeds and front-side buses.

This means that they draw considerably less power than regular mobile processors, and since they boast much lower thermal design power specs, they don't require as much active cooling. These factors contribute to longer battery life for the machines running the chips.

Low-power CPUs are obviously useful for ultralightweight "netbooks," such as Asustek Computer Inc.'s Eee PC, but some manufacturers are also deploying these tiny processors in inexpensive desktop PCs. TriGem USA, for instance, recently announced a new Averatec all-in-one PC based on Intel's Atom N270 processor.

AMD is rumored to be working on a low-power CPU, but it doesn't currently compete in this market. This once again leaves nearly this entire market segment to Intel, although Via Technologies Inc. also has a notable low-power part: the Nano.

Intel

Atom 230, 330, N270, Z500, Z510, Z520, Z530

Core Solo U1300, U1400

Core 2 Solo U2100, U2200, SU3300

Core Duo L2300, L2400, L2500, U2400, U2500

Core 2 Duo L7200, L7300, L7400, L7500, U7500, U7600, U7700, SL9300, SL9400, SU9300, SU9400

Intel's Atom series are single-core processors manufactured using a 45nm fabrication process. They have relatively staid front-side bus speeds of either 400 MHz or 533 MHz, depending on the processor, and their core clock speeds range from 800 MHz to 1.6 GHz. Their biggest attraction is their thermal power design specs, which are as low as 0.65 watts for the Atom Z500 and top out at just 8 watts for the Atom 330.

Several of Intel's Core Solo, Core Duo, Core 2 Solo and Core Duo offerings also fit into the low-power range. Most of these CPUs are more powerful than the Atom, but they're also more expensive; you can expect to pay a premium for computers that use them.

Apple chose the new Core 2 Duo SL9300 and SL9400, for instance, to power its newest MacBook Air models. These CPUs are manufactured using a 45nm process and feature clock speeds of 1.6 GHz and 1.86 GHz, respectively. They each have 6MB of cache (3MB for each core) and front-side buses that run at 1,066 MHz. And yet both chips have a TDP spec of just 17 watts. Apple charges $1,799 for an SL9300-based MacBook Air and $2,499 for the model based on the SL9400.

The Core 2 Duo SU9400 that Lenovo Group Ltd. chose for its ThinkPad X301 has a lower clock speed (1.4 GHz), a slower front-side bus (800 MHz) and half as much cache (3MB). But it has a TDP spec of just 10 watts. Prices for the ThinkPad X301 range between $2,600 and $2,900.

And then there's the Core 2 Solo U2100, which has a TDP spec of just 5.5 watts. Dell tapped this 1.06-GHz processor for several models of its Latitude XT tablet PCs ($1,800 to $2,000), and Sony Corp. selected the CPU for its handheld Vaio UX490N/C micro PC ($2,499).

Via

Nano L2100, L2200, U2300, U2350, U2400, U2500

Via's single-core Nano processor is based on the company's earlier C7 processor and is pin-compatible with that part, which means the chip can be dropped into any existing C7 motherboard. All Nano processors are manufactured using a 65nm fabrication process.

All except the the U2300 have an 800-MHz front-side bus (the U2300's front-side bus runs at 533 MHz, same as Intel's Atom). Nano core clock speeds range from 1 GHz to 1.8 GHz. The trade-off for the Nano's more powerful specs comes in the form of its cooling requirements, which range from five watts all the way to 25 watts for the desktop-oriented L2100.

See specs and pricing for all low-power mobile CPUs, or see all of our quick reference charts.

Michael Brown, a freelance journalist living in Northern California, has been writing about computers and technology since 1987. He can be reached at brownmdj@gmail.com.

Copyright © 2008 IDG Communications, Inc.

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