i would be running about 2 volts through my mobile, but my motherboard won't let me (1.775 max - overvolts to 1.8) and i'm running at ~40C idleish because i don't have my watercooling hooked up ATM.
the core is perfectly safe (and within spec too) up to 2.0 volts if it is a barton core (which yours is)
It is defineately safe to go to 1.7 volts. Try to push the voltage up a little, preferably below 1.85 volts(assuming you have air cooling). Then, you can reach a higher overclock.