I tried those settings given by tommy5761, but sadly the "seams" are still there.

I have an (older) eVGA nVidia 8800 GTS 512 and didn't get those artifacts the last time I played. I was using older drivers at the time, but I don't recall which. It was likely one of these:

* 197.13
* 258.96 (prob this one)
* 266.58

Another thing you might try is making sure Witcher 2 exe is added to the list in the program settings tab . Note that i use the exe to launch the game . The only time i use the launcher is checking for updates or making some changes to the configuration file .
Driver version is 275.33 . The first two pics are my program settings and i`ve also included one for the config. file