I've today installed a new 6970, and had similar problems to many others trying to get the 40xMH speed that others are getting.
I've just managed to do that now, so I thought I'd post another more visible thread to help others.
I've tried different mining clients, although I started with GUIminer / Phoenix & have stayed with it in the end.
I've tried different flags, the usual options, stayed with these flags (nothing unusual in them): -k phatk VECTORS BFI_INT FASTLOOP=false AGGRESSION=11.
I've OCed my card. My original OC settings were: Core 950 (increased to 1000 using Sapphire TriXX), various Mem settings, at first I increased voltage as well to various settings.
None of these OC helped me to jump to 40x MH. When I was running @ 1000MH Core, I was crunching @ 365.
Then I read a thread talking about INC the Power Control Settings in Catalyst. I was running Catalyst 11.8. Setting is located in: Performance / Graphics Overdrive / Power Control Settings. I INC Power Control to +20 (what others had used), but that didn't help... nothing changed.
Then I tried looking for an upgrade to CCC (Catalyst). I found 11.11, installed, INC Power Control, and it worked finally!
I had heard of others using different + settings from +5 -> +20. For me, all had the same effect, so I left my Catalyst Power Control on +10 for good measure.
I'm still OCing, settings I"m using:
Core 950 (TriXX allows more, but Catalyst peaks @ 950 so I left it @ 950)
Mem I underclocked Mem to min that Catalyst went to (1375MHz)
Fan Controlled by TriXX
BTW, I picked up a "custom" phatk script from this thread --- (in case it helps anyone)
"custom" phatk script - supposed to be better & more stable.https://bitcointalk.org/index.php?topic=44971.0
OK, good luck to all 6970 owners! Enjoy 404 MHashing!!