They are roughly at par. AMD does better at lower resolutions because of their cache setup.
With the refreshed cards, AMD is slightly ahead.
NVIDIA's top of the range chip is ahead of AMD's, and the 3080's SKU is at a lower binning point on the bell curve than the 6950's.
Hence NVIDIA would be able to maintain a performance per watt crown at the 6950's price point if it sold its highest bins cheaper.
Given the gap in transistor density, that is an exorbitant architectural delta.
They are roughly at par. AMD does better at lower resolutions because of their cache setup.
With the refreshed cards, AMD is slightly ahead.