I see!
This bug happens only in Vista 64. It is a bug, cause your performance is not in a line with the real performance. For example spl's 05 is normal for those clocks and 03 is way out of the line.
But who can say what is "real" performance? I think it would be best, if top overclokers would not use this combination (Vista 64 + 3DMark03 + 4870X2), cause our rankings in HWbot.org will get nasty otherwise. It is really hard to moderate, if there is some bugged runs in the middle. If the drivers are working "properly" in Vista 64 and the other OS's are bugged, why other 3D benchmarks are not affected at all n Vista 64?
Do we care about real performance or bugged performance?
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