NVIDIA GeForce GTX 880M 's Advantages
Boost Clock has increased by 2% (993MHz vs 975MHz)
More VRAM (8GB vs 2GB)
512 additional rendering cores
AMD Radeon R9 M290X Mac Edition 's Advantages
Released 8 months late
Larger VRAM bandwidth (174.7GB/s vs 160.0GB/s)
Lower TDP (80W vs 122W)