How to turn off vsync in XNA 4.0?

Question

I created a FpsCounter DrawableGameComponent (linked to code, it's longish). It seems to work great, it displays 60.0 fps normally, and if I artificially slow down the game loop then it drops.

Given that my 'game' at the moment is a single sprite that the user can control with the keyboard, it should be capable of a lot more than 60 frames a second. My Game constructor looks like this:

public Game1()
{
    _graphics = new GraphicsDeviceManager(this)
                    {
                        PreferredBackBufferWidth = WindowWidth,
                        PreferredBackBufferHeight = WindowHeight,
                        SynchronizeWithVerticalRetrace = false,
                    };
    _graphics.ApplyChanges();
    Content.RootDirectory = "Content";
}

However, even though the above code seems like it should turn off vsync, it doesn't seem to be. Is there something wrong with my constructor, or perhaps my FPS calculations? Or is there something else that may be limiting the frame count?

Answer 1

if Game.IsFixedTimeStep is true the update method will be called every 1/60 seconds

http://msdn.microsoft.com/en-us/library/microsoft.xna.framework.game.isfixedtimestep.aspx

"The default value for IsFixedTimeStep is true."

Answer 2

It depends on your video card settings (in Windows). I had the same issue and than I found that my nVidia card has its own vsync settings in control panel where vsync can be set to forced-on mode (application settings will be ignored in this case).