Had some of the same issue with running two 6950 I get full throttle only if i give it 2 physical cores and loose performance with one core and a hyperthread. If you want the card at full throttle give it 1 core per gpu if its a dual gpu you will need 2 cores for it, just my experience of it lately... still trying to figure out lasso and when i do ill post my findings... Oh also if you swaped cards around and installed new drivers i found that reseting the project helped out at times..