AMD Radeon Pro W6900X 's Advantages
More VRAM (32GB vs 4GB)
Larger VRAM bandwidth (512.0GB/s vs 112.0GB/s)
4352 additional rendering cores
AMD Radeon Pro W6400 's Advantages
Boost Clock has increased by 8% (2331MHz vs 2150MHz)
Lower TDP (50W vs 300W)