On many of the cards with masked pipes they work somewhere between not at all (card crashes to desktop when you try and run a 3d app) and perfectly. Most have some problems and so produce some artifacts. I'm pretty sure that the cause of the artifacts has nothing to do with the drivers, they are the result of flaws in the GPU (which is one of the reasons why it didn't end up in a 6800GT instead). However i think some drivers can help remove or reduce the artifacts, omega (possibly DNA too, never tried them though) drivers did on my Radeon 9500. This probably has to do with their image quality tweaks or postprocessing or something, the software isn't fixing your broken silicon.
Few things which I have heard (most from techpowerup's softmod FAQ)
Disable Hierarchical-Z (Use a tweak utility, "Rtool" on radeons)
Force Anti-Aliasing (higher the better)
Force Anisotropic Filtering (higher the better)
Force Vsync
Force 16-Bit color
Bear in mind that while most of these reduce performance, a few extra pipelines unlocked will probably increase it quite a bit.
BIOS flashing and changing the card ID does pretty much the same thing as the softmod, and you will get artifacts just the same.
