Fps limitation - does it change anything?

ChriseC

Germany440 Posts

July 26 2014 16:29 GMT

Hey there,

Currently i am using a 60Hz Monitor. For me this is enough so I dont care about getting a better one. However, most games i run in 150-300fps. I thought about limiting the fps by options to safe some resources.
My answer is if there is a difference in running a game on 250fps and using 60Hz or just having 100fps (limited) and using a 60Hz monitor. Will it feel the same or will the non-capped fps still feel smoother?

Thx so far!

FromShouri

United States862 Posts

July 26 2014 16:38 GMT

Yes the refresh rate is basically how many frames the monitor is rated for. (Ie 60hz is meant to showcase 60 fps) that said for the most part you shouldnt have an issue running higher frames on a 60hz monitor. I do remember there was an issue that caused graphics cards to draw sc2 menus at unlimited frames which could damage the card but not the monitor. Honestly unless youre seeing tearing in the screen youre fine. This is where the frame limit option comes in. By limiting the frames to a lower number you reduce screen tearing.

GoldenH

1115 Posts

July 26 2014 19:31 GMT

Ideally you'd have the game fps = your monitor's fps. So you see every frame the computer renders. However it's also acceptable to have a multiple of it, for instance if you have 120 fps and a 60 hz monitor, you'll only see every other frame your game renders. It reduces the lag time between when the frame is rendered and you see it: at 1:1, what you see could be as much as .016 seconds old, while at 120 it would be .008 seconds old, and at .006 at 180 fps, .004 at 240 fps... and that's the maximum oldness, in reality it will be much less, possibly 0!

As you can see, there might be a bump going to 120 hz but after that it gets progressively less useful.

Mongoose

United Kingdom190 Posts

July 26 2014 20:01 GMT

Personally I feel V Sync (capped FPS at 60) makes SC2 lag more. I see it drop down to around 45 for no reason sometimes and stay there (it must be some bug with the engine).

I limit it to 120FPS instead (you can set a custom limit in the config file), and it's perfectly smooth.

Btw, I overclocked my monitor up to 85Hz instead of 60hz and I can notice a huge difference (would recommend you try it out some time)

dukegrieve

Poland15 Posts

July 26 2014 21:02 GMT

V sync does not only limit the refresh rate but it synchronise a frame to be rendered exactly when the monitor refreshes which causes additional lag. It scales as a divisor of refresh rate so its why it sometimes lock at 45fps when your PC doesnt menage to render 60 fps.

Cyro

United Kingdom20326 Posts

July 27 2014 00:05 GMT

I do remember there was an issue that caused graphics cards to draw sc2 menus at unlimited frames which could damage the card but not the monitor. Honestly unless youre seeing tearing in the screen youre fine.

The issue was people with GPU's that couldn't handle running at 100% load, not particularly with sc2. It ran @100% load when not necessary, but hardware is designed to be ran that way. Tearing always happens, at any framerate, unless you are vsynced or gsynced

Monitors refresh in rows of pixels, if you have perfectly evenly spaced 120fps (frametimes are never perfectly evenly spaced apart) then you'd see half of every frame, not every 2 frames.

For example, the monitor would refresh the top half of frame 1, then switch to frame 2 and show the bottom half of that. 60hz just means that it refreshes every row of pixels on the screen sequentially at a rate that takes 1/60'th of a second for 1080 rows (on 1080p) with the frame in front buffer

Personally I feel V Sync (capped FPS at 60) makes SC2 lag more. I see it drop down to around 45 for no reason sometimes and stay there (it must be some bug with the engine).

sc2 doesn't have evenly spaced frames, so to have every frame faster than 1/60'th of a second (needed for 60hz vsync) you often need to be up around 100fps, or even a bit higher. I don't know of any way to cap FPS in sc2 without negative side effects, partially because the engine has no options for it, and the engine is one of the worst out of any that i know of for frame pacing

To answer OP question: A good FPS limit can add very minimal input lag, imperceptible ideally. Very few of them achieve that though, and it's "better" to run unlimited - the only question is how much better, how the implementation of limiting is in the game engine, and how much you care. Limiting FPS in a way where you delay the frames after they are drawn, like using a third party tool or some bad limits is a big NO. Using an in-engine command that's implemented decently like fps_max in the source engine or the one in Wildstar can be good. They work with some other info and do things like sampling input information at better times, instead of instantly sampling input, drawing frame and then holding it in a buffer for ages before you see it (high input lag). Third party programs interacting with games can usually only hold already drawn frames, they don't have other ways of frame limiting AFAIK, which is why it's bad to use them

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