The 3DMark series are probably the most popular benchmarks out there today. A complete 3DMark score includes testing various parts of a system, not just the video cards, for its overall performance.
The numbers here are a little lower than expected. A gap of almost 5,000 points in 3DMark06 and almost 2,000 in 3DMark Vantage separate the 3850 from the 3870.