®®® Posted May 17, 2006 Report Share Posted May 17, 2006 (edited) When you unplug the AC power from a Microsoft Windows XP-based SP2 portable computer, the battery may drain more quickly than you expect. Therefore, the operating system may shut down prematurely. This behaviour was accidentically discovered and extensively described by Tom's Hardware Guide already in January 2006. Microsoft has now released a package of updated USB Host Controller driver files after figuring out (with help of THG?) what causes this behaviour. The portable computer cannot enter the deeper Advanced Configuration and Power Interface (ACPI) processor idle sleep states.This occurs when the USB 2.0 driver leaves the asynchronous scheduler component running continuously. This prevents the processor from entering the deeper ACPI processor idle sleep states, or C-states. C-states save power when the processor is not busy. These states range from C0 to C3 or C4. Typically, an idle portable computer uses the C3 and C4 states to preserve battery power. If an idle portable computer cannot enter or maintain the C3 or C4 states, the battery power drains more quickly. This problem is fixed by installing the download that is available in this article. The patch updates the following files to v5.1.2600.2891 Usbehci.sys Usbohci.sys Usbport.sys Usbuhci.sys and you have the opportunity to read the complete knowledge base article and download the file HERE. Uploaded the patch in 5 main languages. To download the patch for XP localized in German go here. download the patch for XP localized in English go here. download the patch for XP localized in Spanish go here. download the patch for XP localized in French go here. download the patch for XP localized in Turkish go here. You might also want to read this Anandtech article on the subject. Edited July 8, 2006 by ®®® Quote Link to comment Share on other sites More sharing options...
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