Core Duo USB Power Consumption Bug

[pharoah]

Microsoft describes the USB 2.0 issue as follows:

"Windows XP SP2 installs a USB 2.0 driver that initializes any connected USB device. However, the USB 2.0 driver leaves the asynchronous scheduler component continuously running. This problem causes continuous instances of memory access that prevent the computer from entering the deeper Advanced Configuration and Power Interface (ACPI) processor idle sleep states. These processor idle sleep states are also known as C states. For example, these include the C3 and C4 states. These sleep states are designed, in part, to save battery power. If an otherwise idle portable computer cannot enter or maintain the processor idle sleep states, the computer uses its battery power more quickly than you expect."

Basically, if you have a USB 2.0 device plugged in to a computer running Windows XP SP2, your processor will not be able to enter lower power states (e.g. C3, C4 or Deep C4 in the case of Core Duo). The problem is that if a very power-efficient CPU is prevented from going into its C3 or C4 states, then it's consuming a lot more power than it needs to be. It's particularly bad because the problem could exist just by having any USB 2.0 device plugged in, even if you're not using the device.

[Daniel]

Interesting ... and was this issue fixed, or are they still working on it?

[Alan]

yes but normal devices tell windows to power down to the low state and therefor dont have a conflict? When I set up my adds and devices I normally select the running status how I want it to run and dont ussually experience problems with it.

[pharoah]

well from what ive read the fix is going to be a driver update for it its not fixed yet that i know of but will post more as i hear about it

[pharoah]

Munich (Germany) and Westlake Village (CA) - Two weeks ago, TG Daily reported that external USB 2.0 devices may cause certain notebook computers to consume power excessively. In the interest of tracking down the source of the problem, Tom's Hardware Guide worked with engineers from both Intel and Microsoft. Through our extensive collaborative research, we can report that an Advanced Configuration and Power Interface (ACPI) driver in Windows XP Service Pack 2 is the sole cause of the unusually high power drainage observed by all three teams. Today, Microsoft confirmed to TG Daily that it is developing a new patch to fix this particular driver bug, whose nature is somewhat different of those those addressed by earlier Microsoft Knowledgebase postings.

"The TG Daily article brought to our attention that our existing workaround is difficult to implement," said Michael Burk, PR manager for Microsoft's client team. "We also learned that we will need to issue a BIOS update in addition to a Registry modification, to make sure that the fix will be stable." While the existing workaround, which we reported on earlier, is somewhat efficient in regaining substantial battery time for notebooks connected to USB 2.0 devices, Burk told us this new patch will go even further to address these new issues.