A new GB 670OC owner here. First post as well.
So lets start with the numbers. Using AB, but same results with Precision. Newwest drivers - 301.42. Asic 88%
My stock boost goes to 1124(from 980) so the boost is 144, which is way lower than what i read here.
The card is stable at +100 (1224). Using Heaven with extreme Tessellation, 4 AA. The driver crashes at +111.
On the memory side the card is stable at +300 but I think it can go higher.
Thats for now. Pics and stuff later.
As brettjv said, I would say your stock boost is not "way lower", but rather "about average". My GB card had the identical stock boost at 1,124, but I was able to get a +125 offset out of it for a max OC boost of 1,249. Cards hitting 1,300+ are the minority, as are cards that can't break 1,200.