Hi,

I have a new XFX 6970 running on Win 7 x64 with the 11.6 drivers and 2.4 SDK, I'm using guiminer with Phoenix and the following:

-k phatk VECTORS BFI_INT AGGRESSION=11 WORKSIZE=128 FASTLOOP=false

I've over clocked to 975/700 with 1.2v using Trixx I get about ~406 to ~411 MH/s

If I raise the core clock to 980 MH drops to ~400
If I raise the core clock to 985 MH drops to ~250! 
If I go above 985 I get a freeze, I understand that 

Can anyone explain why?

Thanks

Trip