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Windows 7 tips and tweaks

Get a detailed energy efficiency report

There is often a discrepency between what the manufacturer claims for the battery life for a laptop or netboot and what you actually get in real world situations. What is using all the power? Is the laptop capabale of going into sleep mode? What type of sleep mode (there are actually four). Is your desktop computer a power-hungry monster or is it really efficient? Wouldn't you like to know? The answers to these questions are more important than ever with the growing concerns for the environment and global warming.

A utility called powercgf has been in Windows for quite a long time, but the latest version that is in Windows 7 is the most powerful yet and it has some additional features. One of these is the ability to monitor the computer and to produce an energy report.

Click the Start button and enter cmd to open a command prompt window. Now type powercfg -energy and the computer will be monitored for the next minute or so. After this time, a brief report will be displayed on the screen and a more detailed report will be saved as an HTML file. Open an Explorer window, navigate to the folder containing the file and double click it to open it in a web browser to view it.

Windows 7 energy report

The report might highlight several errors. They might not really be errors and they could be settings that are not energy efficient, so don't immediately panic. For example, if you set the power plan in the Control Panel's Power Options to High Performance, then this is flagged as an error. What it means is that the PC is not set to the most energy efficient setting.

You can use the computer when it is being monitored by powercfg, but the report might then state that the CPU utilisation is high. Again, it's not really an error and it's just the PC doing it's normal tasks like running software. Check the error reports and act on any advice, like changing the power mode in the Control Panel.

Right down at the bottom of the report is the active power plan and the power plan personality. You can see if these are not energy efficient modes. There is a section called Platform Power Management Capabilities: Supported Sleep States. These show which of the four possible sleep modes the computer is capable of. If you want to see a detailed description of these sleep modes, go here.

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