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[Pottuvoi]

Remember that only stable V-Synced frame rates are the ones that are divisible with the display hz of the monitor.
So if frame isn't ready in 16.66 ms it misses the refresh and can be shown after additional 16.66ms has gone by and thus is displayed for total 33ms.

Stable framerates. on 60hz monitor as image is displayed every 16.66ms.
60, 30, 20, 15, 12, 10 ...

on 120hz monitor, every 8.33ms.
120, 60, 40, 30, 24, 20, ~17 ,15, ~13, 12, ,10 ...

 

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[Pottuvoi]

I know about that, but I'm only dealing with frame rates above the refresh rate here. ie. if I disabled V-Sync, the framerate would never drop below 65fps (not even below 70fps in my Skyrim example), and yet with V-Sync enabled I can feel minor hitches when it's getting close, and also see these hitches in the form of the FRAPS counter dancing between 60 and 59 for split seconds.

I thought the frame rate might have been dropping below 60fps between the counter's sampling intervals (so I just wasn't aware), but it's not.

Remember even FPS average of 75fps without v-sync wouldn't mean that one of the frames couldn't take more than 16.6ms and thus cause hitch.

 

[Wall Street]

Remember even FPS average of 75fps without v-sync wouldn't mean that one of the frames couldn't take more than 16.6ms and thus cause hitch.

I second this notion. FRAPS reports a one second average frame rate. If the frame rate is 65 FPS, then 50 of those frames would probably have been faster than 60 FPS and the other 15 may be slower.

For example, over the course of a second, 55 frames could render in 15.0 ms each while the other 10 frames render in 17.5 ms each. Although in total you have rendered 55 + 10 = 65 frames over the course of 55 x 15 + 10 * 17.5 = 1000 ms = 1 second (a.k.a. 65 FPS) you can easily see that the 17.5 ms frames won't be done before the VSync would need them and you will get stutter.

 

[BrightCandle]

Change Fraps to measure frame times. If its a real perfect 60 fps then it will always read 16.6ms for every frame. However I suspect when you are getting close to 60 fps what is actually happening is occasional frames are missing the 16.6ms window and actually taking 33.3ms. You can still read an average of 60 fps over the long term with these occasional drops but the image hitches because for a moment the game is running at 30 fps equivalent. Capture those frame times and you'll see the occasional drops that are causing your hitching.

If you really hate this hitching get gsync, its going to just solve this issue for you. You'll be able to work out if you are happy at 45 fps or 40 or whatever as your minimum and it will allow you to play at the maximum graphics that keep to an acceptable amount. It eliminates the problem you have as a vsync on player, the hitching will just be gone. I really recommend based on how you are playing to seriously consider it.

 

[bystander36]

Just remember to put a FPS cap at 60 for Skyrim. That game does not behave correctly above 60 FPS. I don't believe G-sync will change that.

 

[Attic]

My goal is always to run games at V-Synced at 60Hz or 120Hz. That means that I need to maintain a minimum of 60fps or 120fps respectively for an optimal experience. Or does it?

It seems like there needs to be a significant buffer zone, that is, that the frame rate must be substantially higher than 60fps for 60Hz V-Sync to remain smooth. Before I see the frame rate overtly dipping below 60fps, I can feel some minor inconsistencies in motion and these are always accompanied by the FRAPS counter twitching.

For example, in Skyrim I used to have issues with the frame rate dropping into the low 50s in places like Markarth because of a CPU bottleneck. I just tried it on a 4790K, and although I wasn't seeing any troughs in the frame rate, I could feel a slight hitching while panning and the fraps counter was flickering between 60 and 59. I took this to mean that the 4790K was only just managing 60fps. However, when I disabled V-Sync, the frame rate was in fact around 77fps. Shouldn't that have been enough to ensure a flawless V-Sync experience at 60Hz?

I come across this phenomenon a lot; V-Sync starting to get jittery not only when the frame rate drops below the refresh rate (where it all truly goes to hell), but even if the frame rate is merely in the loose proximity of the refresh rate. Apparently, if I want to have a perfectly smooth V-Synced 60fps in Skyrim, there needs to be a potential ~80fps of performance available. Does anyone have an explanation for this behavior?

Nice post.

I like to game locked to 60fps with vsync and I have noticed this same behavior as you. Some games worse than others. I get the judder when fraps starts to do the 59/60 dance. And the difference between the 59/60 dance and locked to 60 is huge.

I take it to mean you need a rig capable of a decent buffer in performance. If you want the 60fps lock you need to be able to drive 80fps. Not sure what the real buffer needed is, but you definitely can't be just at 60fps performance.

IME sometimes it comes down to just one setting to lower. In the New Wolfenstein for example if I turn off screen space reflections I can lock to 60, with it on medium or high the rates do 58-60 in some areas.

Basically at 60fps locked each frame comes in at 16.6ms, under that some frames come in at 33.3ms. If you are at +60fps but dip into 50 sometimes, with 120hz you will be sitting at 60fps and go back to 40fps... when you would be going back to 30fps at 60hz. So 120hz monitor might be considered.


Decent look at g-sync:
here

 

[BrightCandle]

My experience with games like BF4 is that the frame rate can differ from 160 to about 80ish. So you really do need to leave a lot of performance free if you want to ensure that your monitors refresh with vsync on is always maintained. Its really not uncommon for games to vary to half the frame rate or worse so maintaining a constant 60 is like maintaining 120 almost all of the time to deal with the occasional drops.

I don't know how well gsync and skyrim works, I haven't seen anyone test it but I have had first hand experience with the physics mess at 144hz I use. The game is completely unplayable.

 

[omeds]

I cap fps while vsync is enabled to remove instances of judder/stutter in some games. I don't completely understand why it works but it does, been using this method on MGPU systems for almost a decade now.

OP manually cap frame rate in Skyrim to 59 or 60, see if it's any better.

 

[toyota]

60 yes but please not the 59fps framerate cap myth again. all that does is give you the problems associated with having framerates below the refresh rate with vsync on. just panning around will you give a little hitch especially noticeable in a game with no triple buffering. I have tested the crap out of that silly myth and will never understand why some people still advise doing that. I believe it was BrightCandle that backed me on this a while back.

 

[blackened23]

Just remember to put a FPS cap at 60 for Skyrim. That game does not behave correctly above 60 FPS. I don't believe G-sync will change that.

^This is correct, the physics engine is tied to a 60 fps framerate in skyrim. I wouldn't do any type of modifications to vsync in the ini files unless you're doing pure benchmarking, otherwise things will be "off".

Also be sure to enable "maximum performance" for Skyrim via a program profile in the NV CP or a global setting....some less demanding games have been jittery in the past with adaptive (lower clockspeeds for power saving in less demanding 3d apps), although I haven't seen that phenomenon in some time. It happened in darksiders 1 ages ago for me, max performance fixed it.

 

[omeds]

60 yes but please not the 59fps framerate cap myth again. all that does is give you the problems associated with having framerates below the refresh rate with vsync on. just panning around will you give a little hitch especially noticeable in a game with no triple buffering. I have tested the crap out of that silly myth and will never understand why some people still advise doing that. I believe it was BrightCandle that backed me on this a while back.

Not true, at least with MGPU systems.

 

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[omeds]

I'm aware of, and use the capped V-Sync thing (60@60Hz or 120@120Hz), but it doesn't work in this type of situation. I use it more for situations like V-Synced S.T.A.L.K.E.R, where the potential framerate is always way above the refresh, and yet there is still stutter - the cap will fix that.

Yes it helps in the Stalker series, but also helped me in Metro 2033 where my frame rate wasn't significantly higher than the refresh rate. Anyway, it fixed similar issues in Skyrim for me.

 

[Attic]

I think the OP issue is just performance related. You need a TON of horsepower to lock to 60fps with few dips below in some games, you need a lot more to lock to 60fps with no dips ever.

Are you finding that this is from GPU limit or CPU limit on the games with the issue?

Have you tried opening up the 4790k a bit?

Also see here for possible solution in CPU limited games
Video:
https://www.youtube.com/watch?v=_hcuYiqib9I

Thread:
http://www.overclock.net/t/1364200/crysis-3-20-30-framerate-and-performance-boost-cpu-limited-users-only/20