NVIDIA Quadro M5500 Mobile 's Advantages
More VRAM (8GB vs 2GB)
Larger VRAM bandwidth (224.4GB/s vs 32.06GB/s)
1792 additional rendering cores
NVIDIA Quadro P400 's Advantages
Released 10 months late
Boost Clock has increased by 7% (1252MHz vs 1165MHz)
Lower TDP (30W vs 150W)