V-sync???

**Paladin94610** · August 29, 2010, 01:49 AM

Hi, guys, call me an idiot!! I have been playing M2TW for 9 months and I still don't know v-sync. All I knows is V stands for Vertical and sync is a short form of Synchronization. I toggled on and off the V-sync, I don't notice any difference between being on and off. Could you guys explain me a little. Does toggling on decrease performance?

**RabidSheepLegion** · August 29, 2010, 01:53 AM

From what I've seen on other game threads it is supposed to reduce or stop "ripping" in the terrain. Shouldn't really be an FPS hogger if even at all. I always keep it checked because if this "ripping" could pop up, would probably distract me at a bad time and result in getting destroyed lol I bet someone else has more info tho, just putting in some little things that I know tho.

EDIT: Here you go, thanks wiki-pedia! lol

"Vertical synchronization (v-sync, v-synch, vbl-sync, vbl-synch) refers generally to the synchronization of frame changes with the vertical blanking interval. Since CRTs were nearly the only common video display technology prior to the widespread adoption of LCDs, the frame buffers in computer graphics hardware are designed to match the CRT characteristic of drawing images from the top down a line at a time by replacing the data of the previous frame in the buffer with that of the next frame in a similar fashion. If the frame buffer is updated with a new image while the image is being transmitted to the display, the frame buffer gives it the current mishmash of both frames, producing a page tearing artifact partway down the image.
Vertical synchronization eliminates this by timing frame buffer fills to coincide with the vertical blanking interval, thus ensuring that only whole frames are seen on-screen.
Sophisticated software such as computer games and CAD packages often allow vertical synchronization as an option, because it delays the image update until the vertical blanking interval. This produces a small penalty in latency, because the program has to wait until the video controller has finished transmitting the image to the display before continuing. Triple buffering reduces this latency significantly.
VSYNC is also the name of the signal indicating this frame change in analog RGB component video."

- courtesy wikipedia (god!

)

**Paladin94610** · August 29, 2010, 02:28 AM

Thanks. +rep!!

**Caesar Clivus** · August 29, 2010, 02:46 AM

Enabling V-sync can reduce performance depending what video card you have and what graphic settings you have configured in the game. If you've got a decent system though it shouldn't be a problem.

**Freek** · August 29, 2010, 02:47 AM

From what I know vsync has no performance effect, in laymans terms, it means your framerate won't go higher then your monitor refreshrate. In most cases this means it's going to be capped at 60FPS.

**Caesar Clivus** · August 29, 2010, 03:15 AM

VSync solves this problem by creating a rule that says the back buffer can't copy to the frame buffer until right after the monitor refreshes. With a framerate higher than the refresh rate, this is fine. The back buffer is filled with a frame, the system waits, and after the refresh, the back buffer is copied to the frame buffer and a new frame is drawn in the back buffer, effectively capping your framerate at the refresh rate.

That's all well and good, but now let's look at a different example. Let's say you're playing the sequel to your favorite game, which has better graphics. You're at 75Hz refresh rate still, but now you're only getting 50FPS, 33% slower than the refresh rate. That means every time the monitor updates the screen, the video card draws 2/3 of the next frame. So lets track how this works. The monitor just refreshed, and frame 1 is copied into the frame buffer. 2/3 of frame 2 gets drawn in the back buffer, and the monitor refreshes again. It grabs frame 1 from the frame buffer for the first time. Now the video card finishes the last third of frame 2, but it has to wait, because it can't update until right after a refresh. The monitor refreshes, grabbing frame 1 the second time, and frame 2 is put in the frame buffer. The video card draws 2/3 of frame 3 in the back buffer, and a refresh happens, grabbing frame 2 for the first time. The last third of frame 3 is draw, and again we must wait for the refresh, and when it happens, frame 2 is grabbed for the second time, and frame 3 is copied in. We went through 4 refresh cycles but only 2 frames were drawn. At a refresh rate of 75Hz, that means we'll see 37.5FPS. That's noticeably less than 50FPS which the video card is capable of. This happens because the video card is forced to waste time after finishing a frame in the back buffer as it can't copy it out and it has nowhere else to draw frames.

Essentially this means that with double-buffered VSync, the framerate can only be equal to a discrete set of values equal to Refresh / N where N is some positive integer. That means if you're talking about 60Hz refresh rate, the only framerates you can get are 60, 30, 20, 15, 12, 10, etc etc. You can see the big gap between 60 and 30 there. Any framerate between 60 and 30 your video card would normally put out would get dropped to 30.

That is where the performance hit can come from. (Quoted from http://hardforum.com/showthread.php?t=928593)