Intel Xeon E5 2609 's Advantages
Lower TDP (80W vs 135W)
Intel Xeon E5 2643 v3 's Advantages
Released 2 years and 6 months late
Higher specification of memory (2133 vs 3)
Higher base frequency (3.4GHz vs 2.4GHz)
Larger L3 cache size (20MB vs 10MB)
More modern manufacturing process (22nm vs 32nm)