Sometime ago I replaced my HD 4850 graphics card with a HD 7750. Since then, I am experiencing something like a snow effect: slow vertical tiling and quick, flickering white pixels running on the screen (looking closely it's visible everywhere, but generally noticable on dark backgrounds), just like on an old TV. The interesting thing is, it does not occur with every application, but mostly games (for example Mass Effect 3, all Source games, Deus Ex: Human Revolution, even the Steam platform itself). The problem is not visible on screenshots or videos.
I tried another cable and an another monitor, and while the problem was still there, it became almost unnoticable. Also I tempered with the graphical settings and disabling vertical sync makes it much worse, the games mentioned above have became almost unplayable. I'm not sure how this one would be connected to vertical sync.
I also tried to reproduce the problem on my Arch Linux, but I couldn't. As testing the games is rather difficult with the vesa driver (catalyst somewhy performs much, much worse), I could only try Steam in wine, but no snow effect there. I even tried an another, clean Windows 7 installation, but the problem persists on Windows whatever I do.
I really can't figure this one out, sounds like a definite software problem, but internet searches show nothing. Any thoughts?