Intel Xeon D 1531 's Advantages
Released 4 years and 9 months late
Higher specification of memory (4 vs 3)
Newer PCIe version (3 vs 2)
More modern manufacturing process (14nm vs 32nm)
Lower TDP (35W vs 80W)
Intel Xeon E5649 's Advantages
Higher base frequency (2.533GHz vs 2.2GHz)
Larger L3 cache size (12MB vs 1.5MB)