Xeon E7520 's Advantages
Higher specification of memory (1333 vs 3)
Larger L3 cache size (18MB vs 15MB)
Lower TDP (95W vs 130W)
Intel Xeon E5 4617 's Advantages
Released 2 years and 2 months late
Newer PCIe version (3 vs 2)
Higher base frequency (2.9GHz vs 1.866GHz)
More modern manufacturing process (32nm vs 45nm)