I don't claim to be a fountain of knowledge but I'm not a complete moron. I was recently asked these questions, but I didn't have suitable answers.
Processors tend to be manufactured on the same line, usually for their top processor. For example all i3 or i5 start life as i7. When a processor fails certain tests they tend to be 'binned' into a lower category, sometimes having cores burnt out. Why then if they are the "same" processor as higher end models except with modifications to performance are they cheaper? Can they justify the huge price differences considering i5 is an i7 with extra effort put in during manufacture? Surely if it is the same production method, what kind of mark up is on them? What profit is gained on high end or lost on lower end models? Are we being conned?
Well When a batch of CPUs in manufactured, they're cut from the same bit of silicon. The bits toward the middle tent do be better quality, and can perform better. The outer portions tend to be worse quality, so if a CPU can only perform at a certain speed, or can only use a certain amount of cores, it is sold as a cheaper option.
i7's are not marked up, like you think, its the i3s and i5s that are marked down.
In your scenario, at least. I'm not even sure that iProcessors are binned normally like that.
AMD has even stopped binning CPU's, really, and just selling the ones that perform better as 9 series.
Unlocking cores, and cache, like you could in athlon chips a while back, are prime examples of a binned chip. It was supposed to be a Phenom x4, but it didnt quite make standards, so instead of tossing it, it was binned to an athlon x3, or x2, and sold off.
Even with the pristine silicon wafers cut, and nearly perfect vacuum manufacturing there is always a chance for something to go wrong. With the trillions of transistors etched its absurd to think that it will be made 100% with no error.
Intel has a lot of work minimizing the margins off error, but I would guess there is a good percentage of chips that won't be able to be used at all.
some times during manufacturing it's actually cheaper to produce one item but just disable features for the lower end model. or in the processor world it's done as stated above. and i've gotten one of those athlon X2's that i was able to turn on the other two core's and it worked perfect other then the internal temp sensor didn't work. so that was kind of cool. until the heat pipes on my heat sink blew out lol i guess it got to hot because the fan speed never changed.