I'm sorry but I had to chime in on the idea that 1.45V+ isn't safe, I find this to be categorically untrue. My vid on my old x2 4400 was 1.2875, I threw 1.55V at her and she still purrs like a kitten for the past 2+ years...Not to mention my other old 3800+ that I put 1.55V on and guess what? She STILL lives and that is 4+ years ago...while the 3800 may not be the best part of my example(default was 1.4+)I have for the past 8 years had every proc I have owned at 1.55V and their all STILL here and perfectly operable.
Back to the Q6600, again, it comes to down to cooling; if your on air the max VCORE to use is around 1.58V. If its water, 1.63V; if it's phase or LN2 1.7V...
What kills CPU's is:

1. Consistently high idle/ load temps(i.e. idling at 50C+)
2. 500FSB+ 24/7
3. Consistent power fluctuation(irregular voltage regulation, power delivery)
4. God