I have a 2.4b @ stock voltage up at 3.2ghz (SL6RZ) and I think it's safe enough there. If I crank the voltage a little, say to 1.625v, I'm sure it'll break 3.3ghz stable. However, I don't really think that 100mhz is necessary so I like it down there at 3.2ghz. But yes, generally under 1.7v is safe but, IMO, can still slowly deteriorate a processor. Of course by the time it does, technology should have a better toy for you.