Xeon E7520 's Advantages
Lower TDP (95W vs 105W)
Intel Xeon E5 4640 v3 's Advantages
Released 5 years and 3 months late
Higher specification of memory (1866 vs 1333)
Newer PCIe version (3 vs 2)
Higher base frequency (1.9GHz vs 1.866GHz)
Larger L3 cache size (30MB vs 18MB)
More modern manufacturing process (22nm vs 45nm)