Intel Xeon E5 1660 's Advantages
Higher base frequency (3.3GHz vs 2GHz)
Intel Xeon E5 2686 v3 's Advantages
Released 2 years and 6 months late
Higher specification of memory (2133 vs 3)
Larger L3 cache size (45MB vs 15MB)
More modern manufacturing process (22nm vs 32nm)
Lower TDP (120W vs 130W)