It allows them to squeeze that extra 50 mhz out of a celeron or something. Other than that, I can't imagine what they're really buying as heat rises really fast on procs that're doing what they aren't made to do.
As it is, a 400 mhz celeron probably failed at 500 mhz so that's why it's slated for 400. That's how they do some of the processing ability testing on wafer chips after they've been made. Interesting, nonetheless.
