it can cause damage to the CPU, it may not be instant, but it's still there
Yes, it CAN. But only if you use super high voltages like 1.70v and up.
You can take a look at this if you don't believe me
Now, I've re-read the OP's post and realized that he's probably running Sandy Bridge or Ivy Bridge. In that case, I'd put 1.65v as the absolute max. I'd try to get it down to 1.6v if I could.