Xeon X3440 's Advantages
Higher base frequency (2.533GHz vs 2.4GHz)
Lower TDP (95W vs 129W)
Xeon D 2799 's Advantages
Released 12 years and 5 months late
Higher specification of memory (3200 vs 1333)
Newer PCIe version (4 vs 2)
Larger L3 cache size (30MB vs 8MB)
More modern manufacturing process (10nm vs 45nm)