Ok, so we got a new bit of info.... crossposting this partially from the 680 oc thread:
Originally Posted by EVGA-JacobF
Average will be 150-200MHz... only seen a couple that can do 200MHz.
Doesn't sound bad to me at all
Originally Posted by Billy O
I really don't understand all the complaints. What's so bad about a 15%-20% OC. What were people expecting to get?
I agree, in perspective it's actually pretty darn solid for a stock card, stable. There's this pervasive myth out there that all 7970's hit 400mhz oc's all day and night long when it's not the case, most of them are 150-200mhz(at most) bumps for 24/7 stability (for a ~1075-1125mhz operating speed) without making the card into a vacuum cleaner on noise (and even then most of them don't respond to much further voltage bumps, anyway). If we can really expect +150-200 on the GTX 680 as a typical average, that makes clocks of ~1250-1300 generally achievable from a stock of around 1100 max turbo. The OC percentages aren't really going to be that different typically it appears.
We may get a little more from further drivers/tools as well. Assuming the quote above is correct (which I'm sure it's pretty accurate), you're talking an average of say 15% oc (1270 turbo) on a GTX 680 vs. 19% on a Radeon 7970 (1100). With the gtx 680's performance advantage and $50 lower price, it's still a huge contender even for oc'ers using their rigs for gaming/24-7 usage.