Q: I own a Pentium 4 2.6 ghz with a geforce 6800. however, everytime I play Unreal 3 there is no pixel shader effects. I bought the video card at the time when it was released.
A: A 6800 should work fine with Unreal 3. If updating the drivers and playing with the game settings don't do the trick, ask in a U3/Nvidia forum.