The multiplier is not burned into the chip, is is held there in what I assume is ROM-like memory. It is set by activating the chip
s RESET command, and while it is active, sending certain signals to the chip. The problem is, no one but Intel knows what those signals are or how to apply them.
As for it being a hoax, I don't think that's the case here. Sander Sassen works for Hardware Central and has a lot of articles here. The one I am referring to, Supercool to a Gigahertz, is featured prominently in the Tutorials section, but you can also click here:
http://www.hardwarecentral.com/hardwarecentral/tutorials/718/1/ .
I asked him how he changed the multiplier, and his answer was, I admit, a little unbelievable. He said that the chips they used were PIII/500s, and there was a way to unlock the multiplier by drilling into the CPU core in a very specific place, and it was only possible with ultra-high tech (and expensive) drilling equipment. Now I realize how unbelievable this sounds. I mean, for a drill bit to go through the core casing, it would need to have a certain amount of strength that it couldn't be ultra-tiny, but even if it were a half-mm diameter, that would still go through thousands of transistors. And even if you did take it out, doesn't that circuitry need to be there for the chip to function? On the other hand, I can't think of any reason why he would lie about that. I mean, he is a respected contributor to this site. If he doesn't want people to know how to do it, it would have been easier to just say "I won't tell you".
And to Mr. Sassen, if you read this, could you please post some pictures of your drilled CPU's?