iirc, electromigration is just an innate issue depending on the insulation material used, as well as just brute voltage. better cooling won't do much in the way of preventing it, unfortunately.

Also, I think when you summarized in the text after the pics, the voltages for fanned operation and fanless are opposite? I'm sorry if I was just stupid on this one. I need to get to bed; haven't slept in almost 40 hours