V/sync disabled

[tictoc]

Asus p3b-f
P3-500
matrox g400 max d/h (32mb) agp
192 mb pc100

Guys, i'm in an interesting discussion with a gamer about the use of v/sync on/off in respect of more f.p.s in games specifically Falcon4. Now i have always used v/sync off to squeeze some more f.p.s in any gfx intense game and it works great, but he seems to think it's possibly a bad driver/setup thing cause he does not see any difference when he does it (he does not use a matrox card) on any of the six systems he uses. So to help clarify this does anyone else gain f.p.s in games using v/sync off, or do i have a bad driver/setup?

tic

[xortam]

You wouldn't notice any difference if your monitor refresh rate is higher than the FPS rate that the rest of your system can deliver.

[tictoc]

Thats interesting thanks.

tic

[Kruzin]

Lets say you have your refresh set at 80Hz.
That means your screen refreshes 80 times per second.

If your game is able to run at 10000000 FPS, and you have vsync enabled, you will see 80 FPS because that is the fastest your monitor will refresh. Those extra fps are wasted.

If your game is running at 75 FPS, you will see 40fps (a direct divisable of 80) because your screen refreshes 80 Hz, and to sync with the monitor the computer must display at a direct divisable of your refresh when vsync is enabled.

In the same situation (a game at 75 fps and a monitor set to 80Hz), the game will run at 75 fps regardless of the refresh rate of the monitor IF vsynch is disabled, and the computer is not forced to sync with the monitor's refresh rate.

So yes...vsync can have a definate effect on the performance of games. My preference is to disable vsync. The cost of that choice is occasional visual tearing, which you dont get with vsync enabled.


[This message has been edited by Kruzin (edited 12 April 2001).]

[tictoc]

Thanks for the reply, that explains it very well. When playing Falcon4 and i'm in a FLOT situation (front line of troops..sorry if you already knew that), my f.p.s drops to as low as 8 f.p.s (slideshow or what!) with v/sync enabled, but i get as low as 18 f.p.s v/sync disabled, the other guy i'm in conversation with, cannot see any difference with his systems, so he thinks that mayby i have a bad driver/setup. I think i'm right in recalling the G400 max does not totally do trianglular calcs all by itself or something like that, but rather the cpu does some/most of it so i guess there will be more slowups than other gfx cards in high textured areas and as he does not use a matrox and has a faster system than myself then perhaps he is right from his point of view. On the subject of f.p.s, can you tell me the reason for some games having 'framecaps' built in (i'm thinking descent3). Again many thanks for the first rate explaination.

tic

[c0met]

Wow i have the same setup, except a bit more RAM (256), I would be interested to see exactly what OPtions you have on/off and what fps you get in UT.

[tictoc]

Sorry to say i played UT a couple of times back in the day but never got into it enough to check out anything like that (sad or what hehe). The only games i played warrenting speed is Descent3, Forsaken, Falcon4.0 (i guess i like flying), but mostly play Space Empires4, Alpha Centuri, y'know, 2d stuff.

tic

[This message has been edited by tictoc (edited 15 April 2001).]

[Shoyu]

Interesting..

Kruzin, does it mean I'm seeing 30fps if my monitor is 60Hz refresh, and game is 56fps with vsync enabled?

[xortam]

Synching with the monitor refresh rate doesn't force a game rate that's evenly divisible with the monitor rate. First of all, you won't be getting a constant game frame rate; the 56 FPS you cite is an average over time. Second, the video driver will wait for the synch signal and then write some data to video memory during this safe time. The application may be making the request at any time during this refresh cycle and the wait for synch time will vary accordingly. The average game rate will have to take into account the rate of the requests and when in the refresh cycle those requests are made while being capped by the monitor refresh rate.

[Gooshy]

How do I disable vsynch on my G400 DualHead?

tia,

Gooshy

[Admiral]

Use Matrox's Tech Support utility. Under D3D, Force VSync OFF.

Does anyone know how to bring up the console in Undying ? I need to access the advanced settings and tell it to use VSync.
I seem to have better performance with VSync on in UT and games based on it.

[This message has been edited by Admiral (edited 16 April 2001).]