Somewhere around above average to good chip. My 4670k has at the moment 1.27v on the core with a 43 multiplier, highest temps I see in general use (video rendering, gaming and such) is 69-71 celsius (peaks at 72-73 on synthetics, oddly enough), but on air rather than liquid.
Afaik 4670k can handle up to 1.3v relatively safely and mines been running at the 1.27 volts for 2 years now. Even if it was about to blow the fuck up I don't mind, I'm already planning on moving to more efficient processors for rendering and other work-related purposes anyway.
edit: My friend has same generation i7 that's only stable @ 40 and 1.25v. He can't even post into windows with higher multipliers, even at 1.28v.