<< I currently have the P4B266-C version, and I see many with the P4B266 that have 1.8v vcore, while my P4B266-C only has 1.7, Is the C version a castrated version or something? >>
They both have the same 1.7V limit. The difference between them is that the -C version doesn't have USB 2.0, whereas the regular P4B266 does.
Anyone using 1.8V is using I believe it's called the "wire trick" which I'm unfamiliar of. Either way 1.7V is a high enough limit for me 🙂.