Intel Xeon E5 2403 v2 's Advantages
Released 1 years and 6 months late
More modern manufacturing process (22nm vs 32nm)
Lower TDP (80W vs 130W)
Intel Xeon E5 1660 's Advantages
Higher base frequency (3.3GHz vs 1.8GHz)
Larger L3 cache size (15MB vs 10MB)