Vsync is when your video card waits for your monitor to refresh the vertical on your screen. So what? How
is that important? Well, on some monitors, turning off Vsync will stretch the vertical (up and down) too
much and cause tearing in the textures, making the game hard to play. That is
what I experience. But the real question is whether is makes a difference on or off?
Monitors have a refresh rate which is measured in Hertz (Hz) most of the monitors default to 60Hz.. Your
average user will stay on that without knowing that there is better. Most run desktop at 1024x768 and
75Hz. That is about normal for advanced users, even getting into the low category. The higher the Hz the
faster the monitor refreshes the screen making less flicker and much easier on the eyes. But what does
this have to do with games? Most games have Vsync enabled by default... so that means that your game
can't run faster than your refresh rate. If you have a 60Hz refresh rate, you can't get higher than 60 FPS in
most games and usually lower. People that "tune" their system usually turn this off to allow the game to
render as fast as it can, thus making more FPS. For some people there is no stretching and barely any
lickering. But for a lot of people their screens get stretched so far that the game becomes
unplayable. Sure, performance is gained but what good is it if you can't see the entire screen? But some
people are arguing that even with Vsync on, you can get over 60FPS if the refresh rate is 60Hz. Let me
put that to rest by telling you, that is not true at all. If someone claims that they get 200 FPS in a game
that either means that they have a 250Hz refresh rate or Vsync is off and they don't know it.
If, on a given hardware platform, an application is capable of rendering at, say, 75 FPS with vsync off,
optimal refresh rates with vsync on will likely be 75Hz and 150Hz - clean multiples of the raw rendering
frame rate, that come closest to syncing screen refreshes with page flips. At 60Hz or 120Hz, an
application that renders at 75 FPS with vsync off, is likely to deliver only 60 FPS with vsync on. The
"Optimal" refresh rate is not, therefore, the one which Windows chooses, or the highest your monitor
can reach at any given resolution - its the one that comes closest to syncing with page flips. Although
experimentation with different refresh rates is required, it is possible to approach the raw rendering
speed you get with vsync off, but without suffering the visual degradations of tearing.