^ Yep and yep to that.
My old Q6600 is on a 680 and never got past 3.0 stable (still running strong at 3.0 even after almost 4 years though...not bad considering I almost NEVER turn the thing off... (it is my minecraft server now)). Yeah and those temps are fine...tho with that sink I would imagine a bit lower. I'm using a zalman somethingorother from 3 years ago and my load temps are around 50-60c mostly. But I have really good airflow in my old case and always keep my AC cranked up. So...yeah.
If 3.0 isn't completely stable I would dial it down just a tick and call it good...and not worry about crazy overclocks until you can get newer components.