demasoni,
I doubt that the effects of electromigration would be significant in electronics that don't involve such microscopic processes. Electromigration is the wandering of metal atoms into the silicon insulation layers between lines. Given the scale of today's processors, there can be as little as 5 or so atoms thickness dividing those lines. Thus, if the device is operated under extreme temperatures, and those atoms wander, it's possible to create a bridge between lines that should not be bridged, or just cut a line entirely someplace. Also electromigration doesn't ever improve the condition of a cpu. The testing may reveal that a given cpu is capable of handling faster speeds than it was designed to without experiencing electromigration, but in those cases the chip was that way to begin with and it was only revealed through the testing, not a side effect created by the testing.
