3D - 2 simultaneous 60 Hz images, or 2 images at 120 Hz alternating?

It usually stays locked at 60 in 3D Vision. But when it falls below 60 it can still read unusual fps rates which should not be possible using VSync. I don't set VSync manually. When running without 3D Vision, I'd prefer the performance over a little tearing anytime. Just like you. But with 3D Vision enabled, VSync gets enabled automatically. And it makes perfect sense.

The reason why this is not the same experience as without 3D Vision, or why you perceive it differently compared to using VSync without using 3D, is that you need to be aware that you are running twice the framerate which your fps counter reads. An example: If your fps counter would read 45 in 3D Vision, that means your graphics card produces 90fps. Your graphics card has to run in VSync though (trust me in this one, I explained it why it's working this way from a technical point of view), pumping images to your monitor which runs at 120Hz. VSync forces your graphics card to send images to your monitor then which are running in either 120fps (full rate), 60fps (refresh every second frame), 40fps (refresh every third frame), 30fps, 24fps, 20fps and so on. Your screen reads 45fps which aren't actual 45fps, they are 90fps. Your monitor can't show full frames at 90fps, so the next lower full frame rate possible is being used, in this case 60fps (each frame is shown for 2 monitor refreshes).

You are running in 60fps then, which is still pretty much fluid to the human eye. If you had 45fps and used VSync without 3D Vision, they would be actual 45fps and you would get 40fps with full frames being send to your monitor. And those 40fps are of course more choppy, laggy and everything else compared to your 60fps in 3D Vision.

In short: Don't trust your fps counter. No matter if it's the one from rFactor 2, Fraps or whatever program you use.

Here's the same screenshot again how things would look like if you'd really run without VSync:



It's pretty self-explanatory. The only way we can fix this in the near future will be using G-Sync, where the graphics card can make the monitor refresh its panel whenever the graphics card tells it to. Then we'll have no tearing anymore, no stutters and are not locked to those fixed 120, 60, 40, 30 etc. frames.

As long as you're using a regular monitor: You are using VSync in 3D Vision.

 

hiya Robert

re.fps count whilst your in 3d vision yes you right each fps unit represents 2 frames ( 1 per eye ) but this isn't what's in question.

so if you can answer a brief yes or no, have you ever seen your fps counter go above 60 whilst in 3d vision ?

p.s after attempting to run without vsync

 

Yes it can go above 60. And since this is the indication for you that your graphics card is not running in VSync because it goes above 60 I know that this can be misleading.

All I can do is try to explain technically why your graphics card has to run with VSync enabled.

I gave you short yes. Now I want a yes or no from you.

Do you believe that your monitors needs to show completely rendered frames for each of your eye? In other words, does your monitor need to show a completely rendered frame for your left eye when the shutter glasses cover your right eye, and vice versa?

If you answer that question with a yes, you got your answer if your graphics card runs with VSync on or off.

 

hiya Robert

ideally it does need to show a completely rendered frame complete for each eye (alternating), but with sync off it obviously dosnt do this as well, although with the latest drivers it does it decently well (again this is all based on vsync being switched off)

I have no problem with your point of view here although I believe it to be completely wrong & based on a mixture of confused snip bits of information.

in any case if your happy with what you believe & with the way you setup your PC/settings etc then I guess it really dosn't matter.

 

Just provide me an official source which states that this is the case and I'll accept that I'm wrong.

Fully rendered frames aren't ideal, they are the minimum for it to work. I'm sorry I can't explain it any better than I did, using technical explanations, quotes and links to official sources.

 

hi Robert

nvidia advise the use of vsync with 3d vision (since 600 series ) although they pretty much package 3d vision & vsync hand in hand we now as the user have the option,
as oppose to forcing it & giving no reference to vsync (pre 600 series)

as there is so much info on the net surrounding 3d vision pre-600 series gpu's (& since users not being aware they don't have to use vsync .....providing they can obtain decent visual results without it) I can see how you & other users are misled

a lot of PC casual gamers are not bothered about additional lag (that is usually introduced by vsync) so it's simply not an issue ( usually a different story for racing simulators )

if you've witnessed higher fps than your monitors refresh rates then at that time your running with out vsync
(as vsync throttles back fps to match your monitor(s) or fractions it suitably if lower)

with so much confusing information on the net hearing information from someone like me who has been running in 3d for about 4 years ( with forced vsync then without forced but then testing with on / off / adaptive options ) with racing sims is a good source of information

the below information (that is off the net) is a nice read though, again don't get this confused with the shutter glasses being synchronised with the monitor(s) refresh rates

------------------

Definition - What does Vertical Sync (Vsync) mean?
Vertical Sync (synchronization) is a rendering option for a video card. This option prevents the video card from changing the display memory until the monitor is done with its current refresh cycle.

When vertical sync is applied, the rendering engine would match the maximum refresh rate of the monitor if the frame rate being produced is higher than the refresh rate of the monitor. This effectively throttles the maximum generated frames per second of the graphics card.
Techopedia explains Vertical Sync (Vsync)
Vertical sync synchronizes the output video of the graphics card to the refresh rate of the monitor. This can be good when applied to applications that have frame rates significantly higher than the monitor’s refresh rate as this relieves tearing of the image and results in smooth playback. While if the graphics card is outputting significantly lower frame rates than the monitor’s refresh rate, this can result to the video output having judder as the graphics card may miss the monitor’s refresh deadlines.

------------------

p.s there are some users of PC racing sims who do you vsync & seem perfectly happy using it,
although I always advise against vsync this only because of my personal experience of a noticeable increase in lag in some situations (situations / tracks that are more demanding of PC resources ), i (& others sharing the same opinion) may simply more sensative to lag or it may just be the last few hardware configurations highlight lag when using vsync or a combination of the both

I run without vsync ( I'd notice very quickly if it were on & not from the visuals),
my visuals are fairly smooth & fluid ( on latest but one nvidia drivers)

p.s no offence I'm a tad bored writing about this now lol, again I'm happy with you believing what ever as long as your happy etc

 

I don't take offence at all, don't worry, I hope you don't either.

I like having discussions but I simply can't help myself but to try to explain things if I know how they work. I can't find any information how a GPU from a 600 series or newer should be able to produce a clear image using 3D Vision if you don't send fully completed rendered frames to the monitor (for which you need VSync obviously and what all documentation of Nvidia themselves say about 3D Vision - you need VSync or your image will go completely bogus. You can't get "close to the image quality" if you send incomplete frames to the monitor because the bottom part of the image in your GPU's display memory which could not be rendered for the next frame in time for the next monitor refresh is still from the previous frame which was for your other eye. If this image is send to your monitor, you'd see an image partly for your left and partly for your right eye - your head would explode.

I'm going to make a new thread in the Nvidia forums and they will clarify. Afterall this discussion is not about "my opinion versus yours", it's a "what is and what is not".
Spinelli wanted to know whether the card has to run in VSync or not when running 3D because he's afraid he would experience a lot of input lag. An official answer will shed some light on this.

 

hiya

maybe with out vsync many can not get good results ?
I'm using quite a high spec system overclocked & water cooled, I set things up very precise just to get good results
(obviously depends on the software title too ) in 3d vision & no vsync,
a lot of people use low to mid end pcs so maybe it's correct to advise the use of vsync in these cases

many 3d vision users on the Iracing forum didn't know about turning off vsync until I enlightened them & they were happy they could (600 series on) even if it meant turning down/off some graphical options

I really can't stand vsync ( in case you hadn't gathered lol )

 

Hmm... Is it possible that because the newer graphics cards have more memory they basically store 2 different screens at the same time (both the left eye and right eye) and switch between them, similar to double buffering, you can turn VSync off? If you do that, there could be screen tearing between frames for each individual eye, but there won't be any cross over... Let me take a overly simplified example... I know that GPUs have lots of different types of memory and all sorts of confusing things, at least they did a couple years ago when I took a course on GPGPU, but I'll just treat it as one single blob, with a 2x2 pixel screen, and 4 bit grayscale.

Let's say this is what you see:
LEFT EYE RIGHT EYE
AA CC
AA CC

In memory, this might be stored as
AAAACCCC
where the first 2 bytes (the four A's) are dedicated to rendering the left eye, and the last 2 bytes are dedicated to rendering the right eye. I use the underlining to designate which pixels are being sent to the screen at the time:
First frame (left eye):
AAAACCCC
Second frame (right eye):
AAAACCCC

Now, let's say the second image is supposed to look like:
LEFT EYE RIGHT EYE
BB DD
BB DD

With VSync on, it would guarantee this:
First frame (left eye):
AAAACCCC
Second frame (right eye):
AAAACCCC
Third frame (left eye)
BBBBCCCC
Fourth frame (right eye)
BBBBDDDD

With VSync off, it might look more like this:
First frame (left eye):
AAAACCCC
Second frame (right eye):
AAAACCCC
Third frame (left eye)
BBAACCCC
Fourth frame (right eye)
BBAADDCC

So the displayed frame is not guaranteed to be updated, hence you still get some screen tearing but it still would work.

Does that sound like a plausible explanation?

 

That would work indeed, but you would definitely see a lot of tearing this way. In fact, the tearing would be twice as bad (the horizontal distance of the shift in the image when driving through a corner for example) compared to running without 3D Vision because you'd take the information from 2 frames earlier instead of just 1. Adrian said there's no noticeable tearing. I couldn't see any tearing as well when I forced VSync off. From my understanding this indicates that we're seeing full frames, e.g. VSync is on.

 

Do recall that it's running at ~120 FPS, so the screen tearing would be comparable to screen tearing at 60 FPS, which is very common. Also, I figure if your GPU is fast enough, you won't get screen tearing anyway? Basically the difference is that VSync guarantees it's updated, correct?

EDIT: I think I spoke too soon. The ~120 FPS thing is not correct I believe.
I would be surprised though if Nvidia 3D Vision does not force VSync in the background at least for graphics cards with smaller amounts of memory even if you "disable" it. Disabling VSync doesn't make any sense to me unless you do something like what I described in my prior post.

 

I don't really get any ( noticeable ) tearing but I do run fairly high fps too

without vsync things can get juddery although this is greatly improved with latest ( but one ) nvidia driver

(not tried very latest nvidia driver as away snowboarding for a month)

with sync on (I don't use it on but have done just to test) everything is buttery smooth without flaw at all times
but at the cost of increased (at times noticeable) lag

 

I just checked the nvidia site there is a 3d FAQ, it says vsync is recommended at all times. The word "recommended" sounds like it's not forced on....hmmm.

 

The numbers in this huge 3d vision benchmark test seem to indicate vsync was turned off.

http://www.overclockers.com/forums/showthread.php?t=736793

Still hard to find official info.

 

I use 3DTVPlay. My vsync can be turned off (I then get fps reported by game higher than 60). I usually turn it on though otherwise tearing occurs and it looks very wierd.

 

reading between the lines here maybe we do not need to use vsync with nvidia 3d vision .....joke

 

8Do you guys all use 1 Geforce card? Any with 3d and SLI? Trying to gauge what triple screen gaming performance in 3D will be like. I'm seriously thinking of selling my second GTX 780 Ti. Not happy with my general SLI gains compared to my previous AMD crossfire gains (Radeon HD 6990, dual 6970s, triple 6950s), very jumpy/up-and-down fluctuating fps, sometimes worse minimum fps than a single card, and last but not least the NVidia frame pacing that cannot be disabled and therefore you are always running with an entire frame of input lag with SLI (AMD allows you to disable frame pacing, I would normally keep it on for every game except racing sims).

Does the scaling go up with 3D? I saw an official Nvidia guy say that SLI in 3D mode specifically has each card do each eye.... Maybe this will see better SLI performance than just traditional single screen AFR? Or is that what AFR pretty much is anyways, since it's alternating frames?