Intel Xeon E5 2689 's Advantages
Higher specification of memory (DDR3-1600 vs DDR3)
Higher base frequency (2.6GHz vs 2GHz)
Intel Xeon E5 2640 v2 's Advantages
Released 1 years and 6 months late
More modern manufacturing process (22nm vs 32nm)
Lower TDP (95W vs 115W)