Far Cry 2
The Dunia Engine was built specifically for Far Cry 2 by the award-winning Ubisoft Montreal development team. It delivers the most realistic destructible environments, amazing special effects such as dynamic fire propagation and storm effects, real-time night-and-day cycle, dynamic music system, non-scripted enemy A.I. and so much more.
When it comes to gaming we can see that the extra couple hundred MHz on the CPU and the extra memory bandwidth does very little with all setups sitting quite close to each other.