I'm not a graphics guy. I can only make vague suggestions.
The game ships with a user.ltx with certain default values, but if you remove that file it will recreate it with a few changes that often cause trouble. Here are a couple:
These affect the shadows in wide-screen. Set the first to 20 and the second to 1.0:
One other important one:
This causes spinning when waking up or when struck, and exaggerates the headbob. Make this 0.1 or 0.
You can test the shaders by temporarily renaming the gamedata\shaders subdirectory to something else. The usual culprits are SSAO/HBAO (something like that); there are issues with a different one being better than the other for the different brands of video cards. Maybe you can turn off whichever your shader is using.
I also recall a setting for the graphics hardware involving anisotropic filtering (or one of those types of settings) that affected the rendering over distances. I don't think that made the edges of textures have white pixels, though. Maybe tweaking the settings in the Control Panel's graphics applet might help.
There is (was?) an older reference for tweaking STALKER here:
Around all the bushes and trees are these small white dots, which you basically can't see in daylight.
Anyone know of a way to fix this? Maybe it is some setting in one of the mods which can be turned off?
And also, there were some problem with some of the shadows. They were being stretched out, seemingly at random, to cover most of the ground infront of me. If I then moved my field of view, it would go away. Anyone know anything about this also?