It may also have to do with your graphics card. If your card is old, or you have an older version of openGL, old driver, etc; your graphics card can do that. I noticed when I lost all my hdd data in a very bad mistake, I lost my graphics driver, so my graphics card didn't work, and thus if I tried to play a game, not only was it unplayable, but the screen flickered a lot.
Worth checking if your drivers are up to date!