Redmond (WA) - Microsoft quietly released a patch for a power drain bug Tom's Hardware Guide had uncovered earlier this year. The fix promises to increase the battery life notebooks - especially and perhaps only if they are equipped with Intel's Core Duo processors.

It took Microsoft more than four month to come up with a patch that resolves a serious power drain issue in notebooks, if they are connected to USB 2.0 devices. The good news, however, is that the bugfix actually has been available for download since late Tuesday and users who may have been experiencing unusually high power consumption of their notebooks can finally take advantage of the full battery life of their notebooks.

Readers, who remember our initial article that uncovered the bug and a follow-up article that went into more detail, may remember that especially notebooks equipped with Intel's Core Duo processor appeared to be exposed to the bug - battery time loss was much more visible in Intel's newer dual-core Napa platform than in the preceding Sonoma generation.

Microsoft now confirmed this observation to TG Daily and mentioned that the power loss caused by a connected USB 2.0 is "much more pronounced" in Intel-based dual-core notebooks than in the previous, single-core product generation. In a statement sent to TG Daily, the company said that "anyone who is using any USB 2.0 devices while on battery on the latest generation of Intel chipsets (Core series), who is experiencing faster than expected battery drain should install this fix."

One reason for this circumstance is that "the USB code and power management code in Windows XP were designed for earlier generations of hardware and engineering robust solutions to work with all current new hardware as well as full backwards compatibility is difficult," Microsoft said.

Even the development of this bugfix has been more complicated than it may appear. "It is not simple code and it is easy to make a change to enable one scenario that breaks others," a Microsoft spokesperson said. "A USB fix needs to be thoroughly tested both in Microsoft labs, as well as by key OEMs to make sure that there are no regressions on all existing chipset/CPU combinations, or with any of the thousands of devices that can be plugged into USB, and in a variety of combinations, such as hubs. Devices must work initially, must work through suspend and hibernate, and a host of other specialized tests. During the testing, we had at least 4 separate testing resets because a new issue was found that needed to be fixed before broad release," the spokesperson told TG Daily.

According to Microsoft, this fix also applies specifically to users of Windows XP SP2. The upcoming Windows Vista will use an "entirely rewritten USB stack and works fine with these devices without requiring any specific fix," we were told.

The fix is already of a follow-up test in Tom's Hardware Guide's labs. We will publish the results as soon as they are available. Technical detail surrounding the stories can be found in our stories Microsoft driver bug saps Core Duo power and Microsoft to release patch for power drain bug.

The patch for the power drain bug can be downloaded from Microsoft's website.

Source : Tom's Hardware US