Batman: Arkham Asylum is an action-adventure stealth video game based on DC Comics’ Batman for PlayStation 3, Xbox 360 and Microsoft Windows. It was developed by Rocksteady Studios and published by Eidos Interactive in conjunction with Warner Bros.
For our testing we set everything as high as it would go, except for Physx and NVIDIA AA.
As you can see here, all of our cards are topping out around 62fps, which is what the game is limited to without tweaking the configuration.
At 2560×1600 we can see that the XFX Radeon HD 4890 falls behind the slightly higher clocked 4890 2GB. With less than 2fps difference, this is within the margin of error and you would not be able to tell the difference between the two.