So what you are saying is that theoretically you could max clock a single core with TurboMax 3 beyond the regular top frequency?
Well, AFAIK MSR-1999 lets all of the cores run at different frequencies, and the Turbo Boost Max 3.0 is a feature that allows the user to say, "okay, I want to run one of these cores at an even higher speed than what Turbo Boost 2.0 will let it run at."
Anyway, most enthusiasts won't care, if I were running a 6950X I'd disable all of the turbo stuff and push all of the cores to 4GHz+ :)
But this is a good feature for boutique system builders, to allow them to painlessly offer "up to 4GHz" speeds for the 6950X without going through the trouble of manually validating a 4GHz+ overclock.
That said, the very best-of-the-best boutique builders will sell you a water cooled system with a custom loop, with the CPU cranked as high as it'll go. Not cheap, but as they say, "what's good isn't cheap, and what's cheap isn't good." :-)