Intel Xeon E5640 's Advantages
Lower TDP (80W vs 130W)
Intel Xeon E5 1660 v2 's Advantages
Released 3 years and 6 months late
Higher specification of memory (DDR3-1866 vs DDR3)
Newer PCIe version (3 vs 2)
Higher base frequency (3.7GHz vs 2.666GHz)
Larger L3 cache size (15MB vs 12MB)
More modern manufacturing process (22nm vs 32nm)