Intel Xeon E5 2665 's Advantages
Higher base frequency (2.4GHz vs 1.9GHz)
Larger L3 cache size (20MB vs 15MB)
Intel Xeon E5 2609 v3 's Advantages
Released 2 years and 6 months late
Higher specification of memory (1600 vs 3)
More modern manufacturing process (22nm vs 32nm)
Lower TDP (85W vs 115W)