28-Way NVIDIA GeForce GPU Comparison On Ubuntu: From GeForce 8 To GeForce 1080
DiRT Rally would only run on Kepler hardware and newer, here are those results if interested.
Dota 2 from best to worst with OpenGL represents a 27x difference in performance.
The performance-per-Watt shows a 19x spread going back on these GPUs to 2006 with the G8x GPUs.