Xeon E7 2820 's Advantages
Higher base frequency (2GHz vs 1.9GHz)
Intel Xeon E5 4640 v3 's Advantages
Released 4 years and 2 months late
Higher specification of memory (1866 vs 1333)
Larger L3 cache size (30MB vs 18MB)
More modern manufacturing process (22nm vs 32nm)