Intel Xeon E3 1240 v3 's Advantages
Higher specification of memory (1600 vs 4)
Higher base frequency (3.4GHz vs 2.4GHz)
Larger L3 cache size (8MB vs 1.5MB)
Intel Xeon D 1521 's Advantages
Released 2 years and 5 months late
More modern manufacturing process (14nm vs 22nm)
Lower TDP (45W vs 80W)