Intel's Yonah chip is hungry for power

Yonah, a new laptop chip coming from Intel early next year, will run slightly faster than expected, but may also consume more power than its contemporaries.

Intel 'road maps' seen by CNET.co.uk's sister site News.com indicate that the next-generation Pentium M will debut at speeds ranging up to 2.16GHz and possibly 2.33GHz -- slightly faster than the 2GHz or less anticipated by sources in August. Yonah will also come with a 667MHz bus, which is a channel for ferrying data between the processor and memory; today's Pentium Ms feature a 533MHz bus. The price will also be the same.

Yonah chips, though, will carry higher maximum-power-consumption ratings than current Pentium Ms. Most likely, that's because most Yonahs will sport two processing cores, rather than the single core found in today's laptop chips.

While few consumers will ever hit the maximum power consumption levels (also known as a thermal ceiling), the number is an important one to watch. A higher thermal ceiling, in some cases, can mean shorter battery life, greater heat dissipation or a heavier laptop. A higher power consumption number could also erode some of the lead in power consumption that Intel has enjoyed over rival chipmaker AMD.

The 'T' class of Yonah chips, which are expected to be fitted in most business laptops, will come with a maximum power consumption of between 25 and 49 watts. Right now, single-core Pentium Ms top out at 27 watts.

"Forty-nine watts is definitely on the high side. Twenty-five watts is acceptable for a thin and light," Kevin Krewell, editor in chief of the Microprocessor Report, said on Tuesday.

Intel plans for the 'L' class of low-voltage Yonahs to have a maximum power consumption range of 15 to 24 watts -- higher than the 17-watt ceiling found today. The 'U', or ultralow-voltage, models will reach 14 watts at most. Current ultralow-voltage Pentium Ms consume 5.5 watts or less.

An 'E' class of Yonah chips, for gaming systems, will sport a thermal ceiling of 50 watts or greater.

Intel declined to comment.

Power play
The ratings technically do not contradict Intel's somewhat vague statements on Yonah's power consumption to date. The company has said that it will maintain "average power consumption" with Yonah, while boosting performance with dual-core and other features.

Average power consumption is typically far lower than maximum power consumption. Thus, depending on the laptop and the user, there may not be much variation between real-world power consumption in Yonah and that in current chips. The second core in Yonah often won't be running, thereby keeping average power similar to the single-core only models now available. Intel also plans to release single-core versions of Yonah.

A higher maximum power rating, however, can lead to greater energy consumption by laptops. In other words, Intel's 'average' power consumption and yours may vary, particularly if you're playing Battlefield 2 at the airport. Increased power consumption results in shorter battery life.

A raised thermal ceiling can also lead to a heavier laptop, as manufacturers have to increase the size of heat sinks or other components that eliminate heat from the inside of the chassis.

"Average power is important for battery life, but maximum power is important for notebook design," Krewell said.

The ratings could also help AMD. The chipmaker's Turion and other laptop processors have higher thermal ceilings than current Pentium Ms. Higher Yonah numbers will give the bolshy competitor something to bring up in their marketing. However, AMD also plans to deliver dual-core notebook models.

But beyond this, the Yonah family is likely to provide greater performance than current models. Besides having two cores, which effectively doubles the 'brains' on the chip, the new models will run faster and come with faster buses. A few of the Yonahs are also expected to come with virtualisation technology, which aims to let multiple operating systems run on the same computer more easily.

Cost of Yonah
Pricing will stay level, too. The T1600 Yonah -- which runs at 2.16GHz, comes with a 2MB cache and a 667MHz bus -- will sell for $637 (£365). That's the same as the top-end 2.26GHz Pentium M, which has a 2MB cache, or reservoir of memory integrated in the processor for more rapid data access, and a 533-MHz bus.

The road map also identifies a 2.33GHz Yonah, but the chip is not given a model number or price -- an indication that Intel may not release it at the launch, but come out with it later.

The T1500, which runs at 2GHz, will sell for $423, the same as the next-fastest Pentium M. The pattern remains consistent throughout the line. Intel also plans on releasing a 2.33GHz version of Yonah, but pricing was not available.

By the second quarter, analysts anticipate that chips based around the Yonah design will start to creep into the Celeron M line of less-expensive processors.

In addition, Merom, a new notebook chip family, is slated start to appear toward the end of 2006. One change will include a 4MB cache.