Intel Xeon E5 2666 v3 's Advantages
Released 2 years and 6 months late
Higher specification of memory (DDR4-2133 vs DDR3)
Newer PCIe version (3 vs 2)
Higher base frequency (2.9GHz vs 2.4GHz)
Larger L3 cache size (25MB vs 8MB)
Opteron 6278 's Advantages
Lower TDP (115W vs 135W)