They don't, that's the problem.
Sure?
Its a bit early to tell don't you think?
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They don't, that's the problem.
Well my one doesn't and some other review sites like tpu have had the same problems so I wouldn't say ALL 6950s can do 900 on the core.
The maximum I managed was 865mhz. Performance was barely ahead an overclocked 5870. Any higher on the core and games would crash.