NVIDIA GeForce GT 640M Mac Edition 's Advantages
Larger VRAM bandwidth (40.00GB/s vs 14.40GB/s)
128 additional rendering cores
Lower TDP (32W vs 33W)
NVIDIA GeForce 830M 's Advantages
Released 1 years and 1 months late
Boost Clock1150MHz
More VRAM (2GB vs 512GB)