NVIDIA GeForce GTX TITAN 's Advantages
More VRAM (6GB vs 2GB)
Larger VRAM bandwidth (288.4GB/s vs 144.2GB/s)
1728 additional rendering cores
NVIDIA GeForce GTX 660 's Advantages
Boost Clock has increased by 18% (1032MHz vs 876MHz)
Lower TDP (140W vs 250W)