What is vsync?

[Leuce]

Does it give better performance?
And Does it lower power comsumption?

 

[qwertyDS]

set vsync only if you have decent card that can push along with your monitor refresh rate, so basically if vsync is on and you have an 60Hz monitor then it will lock up on 60fps, but if your card cant handle to push 60fps it will lag and you should set it off. also vsync can be enabled if your card can push more fps than your monitor refresh rate, so when this happens the "tearing" appears.
So basically set vsync if you want to lock up your fps with your monitor refresh rate.

 

[Eduello]

No and no. This has already been answered: http://www.tomshardware.co.uk/forum/124553-13-what-vsync

 

[EdwardElric]

Vsync caps the frame rate at 60 fps (usually),
keeping the frame rate in line with your monitor's refresh rate.

Screen tearing can get very bad, and some people notice it more than others.

Vsync also produces mouse lag,
because your PC is dropping frames in order to cap it.

their is a heat increase partially because your GPU strains to achieve the highest fps it can, sometimes 100+,
you generally don't need that many frames so that extra work isn't needed, if you cap your fps at 60, your GPU is doing that much less work.

In the end, if your GPU is running too hot and you're getting more frames than needed, enable Vsync. Unless the game requires precise aiming (fps).

Also, their is triple buffering software which is more resource heavy, but also caps the framerate and doesn't introduce as much lag.

 

[bystander]

A lot of close, but not quite answers.

1) V-sync prevents your GPU from writing to the display buffer (referred to as the front buffer) except between refreshes, which is called vertical blanking mode. As mentioned, it forces the GPU to wait until it can write to the display buffer when the display is not updating its image.

2) Triple buffering with V-sync, allows the GPU to get started on a new frame while waiting on vertical blanking mode by drawing to another buffer. Triple buffering does not affect anything if you are not using V-sync, as the GPU just sends its completed images to the display as soon as their ready.

3) V-sync, with double buffering, which includes the buffer the GPU creates frames on and the display buffer (often referred to as the front and back buffers), will tend to drop your FPS a tremendous amount if your FPS fail to reach your FPS refresh rate. Because the GPU cannot send completed images until the display is finished with its update, and because it is failing to create frames between each refresh rate, it will mostly have to wait 2 refreshes every time, causing 30 FPS on a 60hz display. Triple buffering allows the GPU to get started on the next frame while it continues to wait, preventing the huge drop in FPS.

4) V-sync with triple buffering, DirextX and a solid 60 FPS on a 60hz monitor will result in unnecessary latency. Your GPU will end up sending frames one refresh later, while holding onto a newer one that is complete because DirectX forces the GPU to send all frames to the monitor, even when a newer one is available. OpenGL does not do this.

5) V-sync with triple buffering, OpenGL and over 60 FPS on a 60hz monitor will result in your FPS counter going beyond 60 even though not all frames are being displayed. Unlike DirectX, OpenGL does not have to display all frames. If the GPU creates a new frame before the one that is waiting to be displayed is sent to the monitor, it will throw it out and use the newest one.

Notes:
1) V-sync with DirectX does indeed reduce heat if you are getting more FPS without it.
2) SLI and CF force additional buffers, resulting in a triple buffering like experience, even if the game does not support triple buffering.