Intel Xeon X5660 's Advantages
Higher base frequency (2.8GHz vs 2.2GHz)
Intel Xeon E5 2660 v2 's Advantages
Released 3 years and 6 months late
Newer PCIe version (3 vs 2)
Larger L3 cache size (25MB vs 12MB)
More modern manufacturing process (22nm vs 32nm)