View Full Version : Vertical sync

12-02-2013, 09:10 PM
Can somebody explain why Vsync decreases performance so much in Black Flag? When Vsync is on, I get 25-30 fps at maxed out settings. But when it's off, I get 45-50 fps at maxed out settings. Oh and when Vsync is off, I got strange purple flickering in the map screen (only in the map screen, not actual gameplay). It looked like a screen artifact. It happened to me only once but it still got me worried.

12-02-2013, 09:30 PM
I belive it smooths out jagged edges.

If a line looks like this without vSync: ----__-------_-----_------
Then vSync will smooth it out to this: ----------------------------

vSync can sometimes also make the mice lag behind, depending on how powerfull your machine is.

12-02-2013, 09:44 PM
Vsync does not smoothen jagged edges, that's the Anti-aliasing's job. Vsync means vertical synchronisation: it matches your screen's refresh rate with your VGA's output so that screen tearing is diminished.
Most (if not all) of today's AAA games support tripple buffering, a Vsync technique that allows the VGA to give any number of frames between 30 and 60 as output to the screen (eg 45 or 53). However, AC4 only supports double buffering, which enables the VGA to only give 30 OR 60 frames as an output. More precisely, if your card cannot manage constant 60 frames - even if it drops to 59 for a moment - the in-game double buffering Vsync forces your card to give an output of 30 frames.
That is why with Vsync on you get 30 frames, but with it disabled you get many more.

12-02-2013, 10:02 PM
Thanks guys. And I think I figured out how to get rid of the awful screen tearing when V-sync is off. Enabling adaptive V-sync from Nvidia control panel fixed it for me.
But what about that strange purple flickering in the map screen? It can't be a Graphics card failure symptom, I just got my GTX 660 this summer, so it's still new and I don't have artifacts in any other games. I believe it has something to do with Vsync being disabled, because it never happened when Vsync was on.