Quadro M2000 's Advantages
More VRAM (4GB vs 2GB)
Larger VRAM bandwidth (105.8GB/s vs 32.06GB/s)
512 additional rendering cores
Quadro P400 's Advantages
Released 10 months late
Boost Clock has increased by 8% (1252MHz vs 1163MHz)
Lower TDP (30W vs 75W)