More Detail: Win7 Energy Saving, Timer Coalescing

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Microsoft and Intel have teamed up to promote Windows 7, both claiming that the new operating system (OS) is faster, more energy efficient, and that it takes advantage of Intel-based computers.

Energy Savings for Multi-Processor Systems

The new features relate to the way both the Windows system itself and individual applications draw on the processors at the heart of a computer.

Previously, Windows would make regular automated demands on the processor as a matter of course. This automatically 'woke up' any processor that the application had allowed to become idle because it wasn't needed at that time, which effectively meant that the processor would continue to draw full power even when it didn't need to be active.

Windows 7 is set up so that this only happens with the main processor on a machine, which really does need to be ready for immediate action at all times. On machines with multiple processors, such as many of those produced by Intel (along with some other chipmakers), Windows will allow all other processors to go into a lower-power mode whenever they aren't being used.

Windows 7 "Timer Coalescing"

Another feature, timer coalescing, builds on this work. It involves the way each application is scheduled to make demands on a processor at particular intervals. Timer coalescing tweaks these intervals so that the demands from all the running applications come in as quick a succession as possible, leaving longer gaps in between when nothing is happening -- allowing the processor to go into low-power mode. (Source:

Energy Efficiency with Software Drivers

The feature also works with drivers, the pieces of software which act as the link between a hardware device and Windows.

Because applications and drivers must be specifically set-up by developers to be compatible with timer coalescing, the benefits will vary immensely from user to user depending on both their computer set-up and the applications they run.

In a demonstration this week, Microsoft and Intel showed a Windows 7 machine boasting a 20 per cent longer battery life than an identical model running Vista. (Source:

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