My guitar (SG style, Yamaha) buzzed on the higher frets, on the low E and A strings (mainly the E) depending on how high I have the bridge, it starts around the 7th fret (when fretted) to the 12th, I like a low-ish action though, so at the moment it's buzzing at 7 onward, it stops at the very high frets (maybe 17+)

The buzz itself, is more of a total lack of sustain, from the string hitting/ vibrating against the fret in front of the one I'm pressing- I'm guessing this is a relief problem, but I'm not sure which way to go, as I've taken given the truss allot of releaf, and still the problem persists!

In a month or two, I'll be getting all frets leveled and re-crowned, and a new nut- which I'm hoping will solve all my issues.

Any ideas are appreciated.
In my experience that's the result of low action. Does it buzz even when you raise the action incredibly high? Theoretically it shouldn't, but if it does, then that's either an abnormally large fret or a warped neck/fretboard.

Really though, raising the action should take care of it. Like you said, the cause of this is from the string hitting the fret in front of it in any case.
Yeah, uh-huh...that's what they all say.
Get the frets leveled and you can have your action insanely low and slick, a lower nut helps too. I had my 7 string set up and made proper and it plays real nice .
Ok thanks- when I raise the action it does get allot better, but since I'm normally playing through the amp, with a fair bit of gain, I'll probably leave it as it is for max playability atm.

Month or two should be smooth as butter