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Enabling energy-efficient PCs, handhelds

Posted: 03 Dec 2007 ?? ?Print Version ?Bookmark and Share

Keywords:energy efficiency? PC handheld improved performance? energy consumption?

Peak power performance now requires a holistic design approach to keep energy consumption in check. The last quarter-century has seen enormous progress in the performance and capabilities of servers, desktop computers, laptops and handheld computing devices. Users continue to expect faster operation, greater functionality and lower prices from their computing devices. At the same time, energy costs are rising around the world, presenting an increasingly difficult technical challenge to manufacturers to deliver high performance without dramatically increasing energy consumption. This is not just an issue with industrial users who are concerned about operating costs, but also with consumers who are becoming increasingly concerned about the environmental impact of energy generation and consumption.

Delivering more energy-efficient products requires a holistic effort across all components of a computer system (e.g. processors, hard drives, power supplies and displays). In recent years, advances have been made that dramatically improve efficiency in many of these areas. New techniques have been implemented in chip design for reducing current leakage and varying energy consumption according to demand. New standards have been developed that drive improved efficiency for key platform components such as power supplies and displays, and new methods are being used to improve overall system power management.

As computer systems become more integral to modern life, and the demand for more computing power and functionality continues to increase, managing energy consumption is clearly one of the most important challenges semiconductor and computer manufacturers face.

More performance per watt
Innovations in energy efficiency are an important part of plans to deliver higher performing products. These innovations mean that for a given footprint, developers can maintain performance levels and reduce power consumption compared with previous designs, or gain more performance (more capabilities and compute power) from the same amount of energy consumed. The goal of several companies including Intel is to deliver breakthroughs that can reduce energy consumption tenfold or dramatically increase performance for the equivalent amount of energy.

New designs such as Intel's multicore technology helps ensure that devices can continue to increase in functionality and processing power while improving their overall efficiency. This approach can also help the industry deliver mobile devices with greatly increased capabilities without reducing battery life or devices with dramatically extended battery life that have capabilities similar to current systems. We may see ultramobile PCs that could ultimately achieve 10x lower power consumption than today's laptops. For the industry, this could provide greater flexibility in designing to different form factors, reduced power costs, more performance per watt and more capabilities for any given footprint.

There are a host of new mechanisms and technologies aimed at simultaneously improving performance and efficiency, not just in discrete components, but for devices as a whole. These include techniques for improving the energy efficiency of silicon, designing more efficient components and controlling system power states. This will provide the industry with some of the most power-efficient designs in the world for servers, desktops and mobile devices.

Through the circuitry
In the 1960s, Intel co-founder Gordon Moore forecast a doubling in the number of transistors in a given area of silicon approximately every two years. This prediction now known as Moore's Law has held true for approximately four decades. The ability to continuously shrink circuit sizes is behind this dramatic growth in the number of transistors, but these advances also drive a corresponding increase in power consumption and heat generation over that area. Interestingly enough, Moore raised this prospect in his original paper by saying, "Will it be possible to remove the heat generated by tens of thousands of components in a single silicon chip?"

Energy efficiency improvements in chip design have focused on improving the current flow through the circuitry, reducing electrical losses, and varying power consumption based on demand. A few examples of the techniques used are listed below.

Energy efficiency improvements in chip design have focused on improving the current flow through the circuitry, reducing electrical losses and varying power consumption based on demand. A few examples of the techniques used are listed below.

Strained silicon is a technology that increases transistor performance by inducing strain in the device. This increases current flow and reduces leakage by 5x.The amount of strain can be tuned to meet the needs of the application, giving designers the flexibility to reduce power consumption for a given design, or to significantly improve performance for the same level of power consumption.

Mobile Voltage Positioning and SpeedStep from Intel are technologies for minimizing power consumption of the processor. Initially developed for mobile processors, SpeedStep dynamically scales frequency and voltage based on the need for processing power. By reducing power consumption during lower utilization, savings of up to 30 percent in power and cooling can be achieved. Mobile Voltage Positioning dynamically adjusts processor voltage based on processor activity to reduce power consumption.

While processor power is clearly important, the processor itself typically consumes a small portion of the total power of a desktop PC. Video display devices and power supplies tend to consume the largest portions of power. A number of activities in recent years have been aimed at reducing power consumption of those key components as well.

Reduce backlight power
Display power consumption can be one of the most important factors determining battery life for mobile devices. To address this challenge, Intel participated in an industrywide working group that developed a low-power display panel initiative that reduced display power consumption by more than 30 percent. Intel-based mobile units also incorporate Intel Display Power Savings Technology, which reduces backlight power by up to 25 percent.

Power supplies are also an important part of the equation since losses from a system equipped with an older, less efficient power supply can equal 50 percent of the total system power demand. Several years ago Intel worked with the Natural Resources Defense Council (NRDC) to change its power supply design guidelines to encourage the adoption of more efficient supplies.

Several other techniques have been implemented to reduce consumption in key components. Among the more significant developments are the Dual-Frequency Graphics Technology (Intel DFGT) and Intel Advanced Thermal Manager. Dual-Frequency Graphics Technology enables power reduction to integrated graphics chipsets. Advance Thermal Manager places digital thermal sensors close to each core's hot spot to enable more precise fan control and reduce energy consumed by the fan. Even packaging can play a role in improving energy efficiency. Multichip packaging is being used in handheld products. This requires thinning wafers by grinding the back of the wafer to remove as much as 90 percent of the silicon, allowing for stacking of chips to deliver more performance in the same or less space.

While the processor itself consumes a fairly small portion of the total system power, it can play a critical role in system power management through controlling the operating states of the overall system. The early efforts in improving computer efficiency were primarily focused on achieving low power consumption in non-active states.

System power
Reducing power in non-active states is an ongoing challenge. Computer systems continuously become more complex, with additional add-on features and more functionality, all of which adds to power consumption even in idle mode. Thus, continuing to focus exclusively on idle mode power consumption begins to deliver diminishing returns. One approach that attempts to continue improving overall power management is Intel Active Management Technology (AMT). AMT stores hardware and software information in non-volatile memory and allows continued interaction between a PC and a central network even while PCs are powered off. This is intended to make low power states more useable, since one of the biggest obstacles to broader use of these power management options is an ongoing perception by users that they are incompatible with network operations.

Software tools can also play an important role in overall system power management.

Enterprise computing has become critical to the world economy. Data management and computing are extensively used in commerce, communications, entertainment, and countless other activities. Making servers and data centers more energy-efficient is a high priority.

Servers, data centers
There are several key focus areas for improving efficiency of these systems. These include:

  • Managing energy demand across a system's work cycle, so that it can seamlessly resume operations or react to compute demands as needed, thus enabling lower energy consumption.

  • Consolidating data centers by increasing performance and enabling methods to reliably reduce system power without reducing capability.

  • System provisioning and controls that cater to the activity or load profile can reduce the number of machines needed and drive greater overall efficiency. This can be accomplished through static provisioning (that is, shutting down unneeded drivers and devices) or dynamic provisioning, which enables or disables resources according to need. These techniques optimize the number of machines and the power demand.

  • Using power-aware components such as PCIe technology, which supports low power states and implements comprehensive power management, and PMBus which enables systems to monitor and manage power states of targeted devices.

The need for platforms with the right type of compute power and performance will continue to escalate over time. The capabilities that users expect of PCs are certain to keep accelerating as dramatically as they have in the past 15 years.

With continuing upward pressure on energy prices, future innovations in energy-efficient computing become crucial to enabling the continued expansion of worldwide computer use. Achieving this requires focusing on efficiency across the whole computing platformfrom improvements in silicon design to advanced power management techniques and improved efficiency of supporting components. Clearly, it is important that the energy efficiency of computing and information systems continue to improve dramatically as the sheer number of systems and their functionality continue to grow.

- Tim Higgs, Environmental Engineer
Erik Peter, Platform Strategic Planner
Henry Wong, Senior Staff Platform Technologist and
Jim Kardach, Senior Principal Engineer
Intel Corp.<.>

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