Intel Xeon X5667 's Advantages
Higher base frequency (3.066GHz vs 2.5GHz)
Lower TDP (95W vs 135W)
Intel Xeon E5 1691 v3 's Advantages
Released 4 years and 6 months late
Higher specification of memory (2133 vs 3)
Newer PCIe version (3 vs 2)
Larger L3 cache size (35MB vs 12MB)
More modern manufacturing process (22nm vs 32nm)