NVIDIA GeForce GT 640 Rev. 2 's Advantages
Released 9 months late
Lower TDP (49W vs 130W)
NVIDIA GeForce GTX 660 OEM 's Advantages
Boost Clock888MHz
More VRAM (1536GB vs 1024GB)
Larger VRAM bandwidth (134.4GB/s vs 40.06GB/s)
768 additional rendering cores