Intel Xeon E5 2640 's Advantages
Released 3 years and 6 months late
Newer PCIe version (3 vs 2)
More modern manufacturing process (32nm vs 45nm)
Lower TDP (95W vs 150W)
Intel Xeon X5492 's Advantages
Higher specification of memory (3 vs 3)
Higher base frequency (3.4GHz vs 2.5GHz)