S.T.A.L.K.E.R. - Clear Sky
S.T.A.L.K.E.R.: Clear Sky, is the stand-alone prequel for S.T.A.L.K.E.R.: Shadow of Chernobyl, a first-person shooter computer game by Ukrainian developer GSC Game World. The game consists of a roughly 50/50 mix of new areas and old, remodeled areas from the previous game. The X-ray graphics engine has been updated to version 1.5 and includes DirectX 10 support (later patch 1.5.06 included DirectX 10.1). Additionally, the AI received an overhaul to accommodate the new faction wars feature.
The picture above here, especially in the minimum department is a lot like Warhead. What we see is that the HD 4890 isn't able to break that 30 FPS minimum we need to make a game playable. The HD 5870 on the other hand is able to not only break it at 1680 x 1050, but also at 1920 x 1200.