This isn't usually possible anymore, AMD have clamped down on that.
Also, some people who have tried have bricked their cards even just trying to unlock the shaders, so I'd just accept the performance you get with the 6950 (overclocking it is usually enough to match what you'd have got from unlocking the shaders anyway).
Also, some people who have tried have bricked their cards even just trying to unlock the shaders, so I'd just accept the performance you get with the 6950 (overclocking it is usually enough to match what you'd have got from unlocking the shaders anyway).