several of guru OCers here do not seem to feel 1.55v max on air/1.6v on water is that risky....YES, I know the cpu with those volts will have shorter life span than Intel expects
anything over max rated vcore is risky...now...if you have the money to replace it then don't worry about it.

i paid $890 for Q6600...i hate to burn it up just trying to hold 400 FSb with 1.55+ vcore when i can do 380 FSB with 1.48 vcore...tiny drop in performance is 'ok' with me...there is always someone out there to beat your overclock!