Performance in Third-Person 3D Shooters
Being a multiplatform project, Dead Space is not a very demanding game. The Radeon HD 4830 will be quite able to submerge you into the atmosphere of horror on board the spaceship Ishimura at any popular display resolution including 1920x1200. The GeForce 9800 GT is somewhat faster but the difference cannot be felt in practice.
Tomb Raider: Legend
The Tomb Raider series prefers Nvidia’s hardware, probably due to the more advanced RBE subsystem. Even with the increased texturing capacity of the RV770 core the RV770-based solutions can’t compete with the previous, let alone the current, generation of GeForce cards.
The Radeon HD 4830 makes no exception, but you can use it at resolutions below 1920x1200 to achieve the same level of comfort as with the GeForce 9800 GT. At 1920x1200 neither card can deliver an acceptable bottom speed.