you card is probably defective, considering that you get artifacts even at default clocks, and there is lag in 3d games. You should probably return to the retailer.
I think I may know what the problem is. The default clock speed is too low and I need to set it higher. You could easily do this in the old ATi Catalyst Control Center, but since AMD have released their own version of ccc (AMD VISION Engine Control Center) I don't know how to make profiles.
Can anyone help me here?
the lower clock is to save energy in 2d mode.