NVIDIA GeForce 840A 's Advantages
Boost Clock has increased by 41% (1124MHz vs 797MHz)
Lower TDP (33W vs 122W)
NVIDIA GeForce GTX 780M Mac Edition 's Advantages
More VRAM (4GB vs 2GB)
Larger VRAM bandwidth (160.0GB/s vs 16.02GB/s)
1152 additional rendering cores