VIA PowerSaver™ Technology

Modern computer operating systems can now dynamically monitor the performance needs of the user and accomplish tasks with the lowest possible power consumption.  However, this adaptive power management requires a new level of sophistication in the processor architecture in order to take practical advantage of it. VIA processors employ VIA PowerSaver™ technology to deliver rapid transition control of performance and power settings.

Whilst operating a processor at high clock speeds gives better performance, when performing non-CPU intensive tasks, such as web browsing, network data access and using productivity tools, the same processor can be run at a lower frequency, thereby generating less heat and consuming less power. There is a corresponding reduction in voltage, further reducing power consumption and heat generation.

By enabling smooth transition between maximum and minimum processor speeds within one clock cycle, VIA PowerSaver™ firmware reduces both power usage and dissipation, resulting in longer battery life for notebooks, extended processor life, and reduced noise generated by cooling fans.

In combination with VIA TwinTurbo™ technology, these transitions can be made within a single processor clock cycle, providing the most rapid change of state possible to avoid performance latency and unnecessary power use.

How VIA PowerSaver™ Works

Three factors need to be considered when looking at the energy implications of using a given processor frequency:

• The performance provided by the frequency
• The latency required to enter and exit the state
• The power consumed by the processor in the state

VIA PowerSaver™ technology dynamically adjusts processor clock speed to the frequency requirements of the running applications. By stepping frequency up and down in large or small increments within a single clock cycle, the processor is able to reduce periods of system unavailability ensuring seamless running of real-time operating systems and reducing latency issues.

For desktop and embedded processors, VIA PowerSaver™ transitions between the top processor speed and the front side bus (FSB) speed. For mobile processors, there are incremental speed stages (see VIA Enhanced PowerSaver™ below).

Measurements show that computational energy can be reduced by up to at least 40% when compared to fixed-frequency operation, not only resulting in reduced power expense, but also greatly aiding efforts to reduce the amount of CO2 that is emitted into our environment.

VIA Enhanced PowerSaver™ for Longer Battery Life

While energy efficiency enables savings of heat and power in the desktop and embedded spaces, for mobile computing it is essential to extend battery life and reduce the time between recharges. For the VIA C7-M mobile processor family, including the ultra low power version for ultra mobile devices (UMDs), VIA Enhanced PowerSaver™ meets the needs of mobile computing.

To allow the operating system to save the maximum power at a wide range of frequencies, the VIA Enhanced PowerSaver defines a set of Performance States (p-states). All of VIA's mobile and ultra mobile processors support intermediate p-states, so the BIOS contains a table of up to 16 frequencies with the corresponding voltage that is required for reliable operation at that frequency.

The table shows the available Performance States speed grades of the 2.0GHz model of the VIA C7-M processor. Note the flexibility to step-down the CPU frequency by up to 75%, with a corresponding reduction in power. Also note the dramatic power benefit from voltage scaling.

P-State Information for the 2GHz VIA C7-M Processor

It takes a specially-screened, high-performance processor to achieve these clock rates at such low voltages and still provide the performance required for popular applications. VIA C7-M mobile processors combined with VIA Enhanced PowerSaver™ provide the optimal solution to mobile computer OEMs, and enable consumers to enjoy their computing and communication for longer between recharges.

Certified for Energy Efficiency

Around the world, environmental awareness is prompting governments to encourage manufacturers to produce more energy efficient products, both in order to reduce the strain on the power generation infrastructure as well as the amount of carbon dioxide being emitted into the atmosphere. Progressive governments and concerned organizations are leading the way with certification programs to recognize the achievements of vendors in bringing down the power use compared to current appliances.

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VIA PowerSaver™ technology has just been certified for energy efficiency by the China Standard Certification Center (CSC), China's equivalent of the Energy Star program in the U.S., which commended VIA PowerSaver for providing both environmental and economic benefit. The first technology of its kind to receive this certification, VIA PowerSaver can help contribute to the environment as computing becomes more widespread in this and many other emerging nations.