Intel Xeon E3 1558L v5 's Advantages
Released 6 years and 2 months late
Higher specification of memory (2133 vs 1333)
Newer PCIe version (3 vs 2)
Higher base frequency (1.9GHz vs 1.866GHz)
More modern manufacturing process (14nm vs 45nm)
Lower TDP (45W vs 95W)
Xeon E7520 's Advantages
Larger L3 cache size (18MB vs 8MB)