Intel Xeon E5645 's Advantages
Lower TDP (80W vs 85W)
Intel Xeon E5 2620 v3 's Advantages
Released 4 years and 6 months late
Higher specification of memory (1866 vs 3)
Newer PCIe version (3 vs 2)
Larger L3 cache size (15MB vs 12MB)
More modern manufacturing process (22nm vs 32nm)