Been dealing with very similar thing and curious if anyone has any guidance to push me just a bit further :
After several BIOS flashes and fresh installs of many catalyst versions I am currently running stable at 700/khs on a 925/1275 speeds with TC of 8192 on 13.6 beta 2 catalyst and cgminer 3.2.2. I flashed from a OC to TO BIOS to get a default of 1100/1500 instead of the 1000/1375 it came with. It allowed me to shoot into the high 750plus kh/s speeds but would constantly crash and go to black screen 5 minutes later when using 1042/1500 and was about to hit 90temp before I shut it of.. Found the 925/1275 on a forum and that brings me to a stable 700 kh/s with a 82-85 temp still being in the case with no risers(side panel off).
Does anyone have any configs for cgminer to get above 705 kh/s using a GPU engine speed of less then a 1000? Making progress one kh/s at a time. If I could get 30-50 more Id be such a happy camper...thanks guys!
What exactly revision card you got? What is the bios you put into it?
I also have a Gigabyte 7970 OC rev 1.0
