Intel Xeon E5 2640 's Advantages
Lower TDP (95W vs 135W)
Intel Xeon E5 4655 v3 's Advantages
Released 3 years and 3 months late
Higher specification of memory (2133 vs 3)
Higher base frequency (2.9GHz vs 2.5GHz)
Larger L3 cache size (30MB vs 15MB)
More modern manufacturing process (22nm vs 32nm)