How can Intel Know Who's been naughty or nice?

Great question. I have only an idea.

Let's say you went beyond intel spec, letting the CPU hit 90C and raising the voltage to 1.8V. This cpu will die within 2 years with normal use, I'm quite sure of it. The cause of the death would be electro-migration, in which the high voltage and heat would speed the process up. I'm sure Intel will check for signs that the cpu has died from electro-migration (from the wires and such) and conclude that the cpu was not within Intel specs.

I'm also quite sure that more than 99% of the cpus (in retail) is not defective, so the chances of a cpu just dying from defective parts is slim and none.

Of course there are people who uses their pc day and night, stressing the components continuously, and perhaps a weaker part of the cpu would give away. I'm not sure it would die from electro-migration though.

can electro-migration only be sped up through high temps and voltage? What about ambitious FSB or 24/7 use? I like using pc to do folding if I'm not using it. How does under-volting effect electro-migration? My first pc was an 86 from 86. It was 24/7 until the 286, but was still used. Last I checked, the thing still lives:-)

86 huh? Well, the manufacturing process is much larger, so electro migration isn't a large issue for it. As the manufacturing process gets smaller and smaller, electro-migration becomes a much larger issue. 45nm is where we have to start seriously worrying about it. As we get to 32nm...we'll see.

Every electrical component suffers from electro migration. Heat and voltage is the key to reducing the process, so under-volting will slow electro-migration down (Less voltage = less current = less particles being 'migrated'). Lower voltage also lower heat, so the effect is exponential (my guess).