Intel Core Duo USB Issue: A Mischaracterized Bug

The engineers responsible for Intel's Core Duo processor and Centrino Duo platform are a bit frustrated.  Years of hard work leading up to the platform's launch in early January was first plagued by the problem of availability.  Core Duo and Centrino Duo notebooks are still not widely available, and that will continue to be the case at least for another week or two.  Outside of availability, another even more troubling problem crept up - could it be that the Core Duo platform had a bug that significantly reduced battery life when paired with any USB 2.0 device?  The folks at Tom's Hardware originally uncovered the issue, when they noted that battery life on their ASUS Core Duo notebook dropped dramatically after merely connecting an external USB 2.0 device. 

How much more frustrating could things get?  After spending years of work on a new mobile CPU and platform, your customers still really can't buy them and the one thing that everyone remembers about them is that they have some sort of a bug that reduces battery life.  When you've spent a good deal of your design time trying to increase battery life, having a reputation of decreasing it before notebooks are widely available has to be a tough pill to swallow. 

However, the case isn't as open and shut as that; the original test data indicated that this was primarily a Core Duo problem, while Microsoft insists that the problem should affect all notebooks.  The other issue is that, until last week, every single Core Duo platform that we could get our hands on was pre-production.  There's also the question of whether or not the problem is caused by the actual USB device used.  And finally, amongst all of this debate and finger pointing, a temporary solution actually existed, just begging to be tested. 

We set out on investigating this issue immediately after it was discovered, but soon found out that it was a lot more complicated than we thought upon first glance.  We've spent almost the past two weeks performing non-stop battery life testing on five notebooks with up to 4 different USB devices, testing theories, trying to pinpoint exactly what causes this problem and testing Microsoft's fix.  What follows is the process that we went through in our labs when faced with this strange bug.