Thank you very much for the info bichi, precisely what I wanted.

Tried out 2206 on my G0 Q6600 but too bad, Vcore values remained exactly the same as 2205 previously, varying between 1.15V idle and 1.25V load. So it looks like they upped the Vcore for B steppings only. Or perhaps diff. P5W revisions play a part, mine is the earliest 1.85V revision.