The open question: Why Core Duo?
While Microsoft's Knowledge Base article is conclusive and states that the current ACPI driver is a "known problem," we are still scratching our heads why only our Core Duo/945-based platform provoked the error and not the Sonoma or the AMD/ATI Radeon platforms. Also, according to the Windows Performance Monitor utility, the Core Duo notebook showed a similar deeper sleep performance as the single-core Sonoma platform: The dual-core notebook remained in the "C3" sleep state for 99.82% of the time during the USB 2.0 device was connected, the single-core notebook 99.84% - which may indicate that there was no difference of when certain sleep staes were reached. However, we were not able to confirm whether the dual-core notebook in fact reached one of its two remaining "deeper sleep" states (C4 and C5).
For now, we are told that the solution to the matter could be simple: a simple addition of a single key to the Windows System Registry. At the time of this writing, neither Microsoft, Intel, nor Tom's Hardware Guide has had the opportunity to attempt this suggested fix to our Napa system. The engineers of Tom's Hardware plan on testing a Napa notebook with modified Registry settings and we will publish our findings as soon as they are available.
Intel's Greg Myers did not have an explanation, why we have seen two different effects of USB 2.0 on our single- and dual-core platforms. "This is an issue that is not specific to Napa. We expect this problem to occur on any system - whether it is a Sonoma or any other system. We are still not sure why you have been seeing a different result in the Sonoma notebook," he said.
However, the reason that one notebook is impacted by the bug and the other is not, may be be that there are several more components that can cause excessive power consumption through USB 2.0. "It is just one piece of the puzzle," Myers said. "All the vendors have to design their products according to the power management specifications. If one componet is not working properly, the whole system may be impacted."