Screen tearing because of Vsync

[Niels De Clercq]

Good night everyone,

A friend of me told me to put Vsync off in League of Legends. Since then i have huge screen tearing. Whenever i put this back on, i don't have any screen tearing. Is putting Vsync on bad? If yes, what does this do?

Thanks in advance!

 

[dark_lord69]

It is bad for some games and good for others. Some games that experience tearing may do better with v-sync on. I've been a computer tech for many years and there honestly is no perfect answer to your question.
I would say though that it's not "Bad".

I use vsync for Diablo III and Starcraft but keep it turned off for some of my racing games.

Bottom line: Trust your eyes.. If it's tearing try turning vsync on and see if it gets better.
Also... If a game seems choppy (low frame rate), try turning it off as you may gain some extra FPS.

Why so many people think it's just bad: If you turn on VSync, games are locked to 60 FPS at most (Unless you have certain gaming monitors with higher refresh rates 144Hz for example would have a max frame rate for vsync at 144 FPS). But any game that is running at 60 FPS doesn't look choppy so having it on is fine. However, if you turn it on and your video card can't do 60 FPS or more for that game, you will end up with a frame rate locked at a fraction of the 60 FPS that you could get as a max.

Example: My video card is pretty decent and I could run Diablo III beyond 60FPS so when I turn on VSync it's just stuck at 60 FPS because that's my TV's refresh rate (60Hz). If my video card wasn't very good and I could only get 35 FPS then my FPS might lock down to 30 FPS which can feel a bit choppy (but still playable) if you ask me.

Why tearing happens:
The limitation is the monitor you are using. Years ago CRT monitors had refresh rates that went up to and above 120Hz. Today most LCD (or LED) monitors are stuck at 60Hz for the refresh rate. Some gaming monitors can go up to 144Hz for the refresh rate which if vsync was turned on would allow for a much higher frame rate.

What happens:
Your frame rate is high enough that the game could have significant changes before the next screen refresh that shows the most current image. (Happens most when screen changes or moves quickly.) It all happens very fast but causes the tearing you see unless you turn on vsync. Screens with higher refresh rates, refresh so fast you can't visually see any issues. And since it's happening at a faster rate the game's video output has likely made very few changes before the next screen refresh.

 

[bystander]

A quick run down of the benefits and drawbacks of V-sync. The above is missing certain points.

1) The only way to stop tearing with video games is V-sync or G-sync (soon there will be freesync). The latter require special monitors. V-sync forces the GPU to only send frames between refreshes so you don't get multiple partial images on the screen, as a result of the GPU sending new images partway through the monitors refresh.

2) As mentioned above, if you cannot maintain your refresh rate in FPS, you may experience some stuttering, as a result of some frames only waiting one refresh to be displayed, and others have to wait 2.

3) If you do maintain your refresh rate with V-sync, on a DirectX game (almost all games), you will incur a frame worth of latency. OpenGL does not have this issue.

4) The system for V-sync was designed around the idea that a monitor has to update it's image at a fixed rate. This was due to CRT's and LCD's have followed suit. G-sync and soon to be Freesync changes this, as LCD's do not have to update at a fixed rate, so some special monitors make it so the GPU dictates when the monitor updates it's image, giving you the best of both worlds. No tearing, and no stutter, though the latency can still be a problem if you hit the max refresh rate of the monitor (FPS cap can fix this).

A compromise comes in the form of adaptive V-sync for Nvidia cards, and Dynamic V-sync for AMD cards using RadeonPro (aftermarket software). These allow V-sync to be on when you reach your refresh rate, and turn it off if you fail to. This helps prevent the stutter that V-sync can cause, when you fail to reach your refresh rate.

What is best is up to you. Your friend gave his opinion, which sounded a little more like a fact to you. It's an opinion, and you are free to do as you think is best.