NVIDIA GeForce GT 640 's Advantages
Lower TDP (65W vs 250W)
NVIDIA GeForce GTX TITAN BLACK 's Advantages
Released 1 years and 8 months late
Boost Clock980MHz
More VRAM (6GB vs 2GB)
Larger VRAM bandwidth (336.0GB/s vs 28.51GB/s)
2496 additional rendering cores