Intel Xeon D 1520 's Advantages
Released 7 years late
Higher specification of memory (4 vs 3)
Newer PCIe version (3 vs 2)
More modern manufacturing process (14nm vs 45nm)
Lower TDP (45W vs 50W)
Xeon L5420 's Advantages
Higher base frequency (2.5GHz vs 2.2GHz)