NVIDIA GeForce GT 640M Mac Edition 's Advantages
Lower TDP (32W vs 80W)
AMD Radeon R9 M290X Mac Edition 's Advantages
Released 1 years and 9 months late
Boost Clock975MHz
More VRAM (2GB vs 512GB)
Larger VRAM bandwidth (174.7GB/s vs 40.00GB/s)
640 additional rendering cores