NVIDIA GeForce 840M 's Advantages
Released 5 years and 7 months late
Boost Clock1124MHz
More VRAM (2GB vs 1024GB)
320 additional rendering cores
Lower TDP (33W vs 75W)
NVIDIA GeForce 9800M GTS 's Advantages
Larger VRAM bandwidth (51.20GB/s vs 16.02GB/s)