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Nvidia FAST Sync, what pc gamers have needed for decades

ACH1LL3US

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So with the new Pascal showing in the GTX 1080, they happened to show what will be available in the next driver release for Pascal, Maxwell and fermi cards.

It is called FAST Sync and what in laymans terms does is have vsync off and no tearing and just a smidge more input lag then just vsync off.

So for me I play pc games on an LG oled screen 1080p, currently my option was turn vsync off and get low lag but horrible screen tearing or enable vsync and get about 4-5 frames of lag for every game.

This new option is amazing and exactly what we have been wanting.

Please keep in mind that Gsync is for under 60fps gaming and fast sync is for over 60fps gaming and does not require a special tv, monitor or input!!

I play alot of console ports that are hard locked to 60fps, I am not sure how this will work for those games, I would imagine turning vsync off in games like SFV or Need for speed most wanted would cause tearing and fast sync would remove the tearing and lower the input lag substantially.

Below are two links, one is a video explaining this new tech and the other is input lag of pc games with and without vsync.

What say you GAF?

fast sync video:

https://m.youtube.com/watch?v=WpUX8ZNkn2U

Pc input lag with and without vsync:

http://www.displaylag.com/reduce-input-lag-in-pc-games-the-definitive-guide/
 

23qwerty

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Jun 29, 2009
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Please keep in mind that Gsync is for under 60fps gaming and fast sync is for over 60fps gaming and does not require a special tv, monitor or input!!

gsync is incredibly beneficial over 60fps as well.

is this something that's going to be available only to the new cards?

ah, sounds like it

We are doing something different now with Pascal.
 

JoeyJungle

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Aug 24, 2011
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Please keep in my Gsync is for under 60fps gaming and fast sync is for over 60fps gaming and does not require a special tv, monitor or input!!

Gsync works for all framerates the display is capable of displaying, even sub-30.

Is there any substantive difference between fastsync and borderless window mode? Doesn't triple buffering basically accomplish the same thing? Or am I misunderstanding how borderless windows work?
 

ACH1LL3US

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gsync is incredibly beneficial over 60fps as well.

is this something that's going to be available only to the new cards?


Yes this will be available to the 900, 700 , 600 and 500 series cards.

I had thr Asus ROG 1440p gsync monitor, from what I understand and what Nvidia states it is mostly for under 60fps.
 

23qwerty

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Jun 29, 2009
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Yes this will be available to the 900, 700 , 600 and 500 series cards.

I had thr Asus ROG 1440p gsync monitor, from what I understand and what Nvidia states it is mostly for under 60fps.

Oh, neat. But nah Gsync is super beneficial over 60fps as well. Being able to play at completely arbitrary framerates up to 144hz without stuttering/tearing is a huge benefit.
 

Felix Lighter

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Oct 2, 2007
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Gsync is for all frame rates. It eliminates tearing by dynamically changing your monitors refresh rate to match the frame rate. It is the perfect solution for all situations. Little to no added input lag, zero judder and every ounce of performance your GPU is capable of.
 

tuxfool

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Oct 21, 2014
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I play alot of console ports that are hard locked to 60fps, I am not sure how this will work for those games, I would imagine turning vsync off in games like SFV or Need for speed most wanted would cause tearing and fast sync would remove the tearing and lower the input lag substantially.

If you play console games locked to 60 this won't much of a difference. There are no spare frames there to be discarded. The engine is writing to the buffer at its top rate, meaning it is already presenting the most recent response to input that it possibly can.
 

Collateral22

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I play on a 32 inch TV, This means I could play at unlocked framerates, get a lot less lag and no screen tearing? If so awesome.
 

jediyoshi

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Isn't fast sync's main strength if the game is running 150+ fps?

Input latency wise, the point is that it's always beneficial versus vsync on.

Not sure what the difference between this and triple buffering is though if the end result is having a separate buffer with a fully rendered frame waiting to get displayed.
 

ACH1LL3US

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If you play console games locked to 60 this won't much of a difference. There are no spare frames there to be discarded. The engine is writing to the buffer at its top rate, meaning it is already presenting the most recent response to input that it possibly can.

I Know but turning vsync off I would assume would lower the input lag and have no tearing right??
 

Gbraga

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Aug 6, 2009
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I Know but turning vsync off I would assume would lower the input lag and have no tearing right??

Not exactly off, it'll be a separate function, because they can't remove real v-sync off, since a lot of people will still prefer the slightly lower input lag over fastsync, but yes, you are correct.

The difference between vsync on and off for SF V is MASSIVE, even though it's still locked to 60fps.
 

Felix Lighter

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Turning off vsync and locking framerate to 60 isn't going to fix tearing and infact could result in some terrible tearing. A new frame cannot be drawn until the screen completes a refresh to prevent tearing. If a new frame is completed halfway through each screen refresh, you'll get constant tearing even though the frame rate and refresh rate match numerically but are not insync.
 

tuxfool

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Oct 21, 2014
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I Know but turning vsync off I would assume would lower the input lag and have no tearing right??

See the answer above. This method is triple buffering. It benefits those that like to run games at higher frame rates (and input sampling) than the monitor.

This allows them to do that without tearing.
 

ACH1LL3US

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I play on a 32 inch TV, This means I could play at unlocked framerates, get a lot less lag and no screen tearing? If so awesome.

That is correct!

If you have a gsync monitor this probably wont be as important but for those on tvs or monitors this will be a huge blessing!!
 

ACH1LL3US

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Not exactly off, it'll be a separate function, because they can't remove real v-sync off, since a lot of people will still prefer the slightly lower input lag over fastsync, but yes, you are correct.

The difference between vsync on and off for SF V is MASSIVE, even though it's still locked to 60fps.

With vsync off on sfv you get tearing, when using fast sync we wouldnt have tearing and the inout lag would still be seriously reduced!

Did anyone actually watch that video that I linked? Tom explains this is NOT triple buffering because triple buffering still has serious input lag!
 

ACH1LL3US

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Turning off vsync and locking framerate to 60 isn't going to fix tearing and infact could result in some terrible tearing. A new frame cannot be drawn until the screen completes a refresh to prevent tearing. If a new frame is completed halfway through each screen refresh, you'll get constant tearing even though the frame rate and refresh rate match numerically but are not insync.


Fast sync will remove the tearing though in this scenario.
 

tuxfool

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Oct 21, 2014
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Fast sync will remove the tearing though in this scenario.

It will still potentially lag because it has to synchronize the writing to the framebuffer and having it ready for vblank.

The engine may write into that buffer at any time within the 16.6ms between vblank. If it writes in the middle of that period you're getting 8ms lag, but if it writes toward the beginning you're getting mostly a frame of lag.
 

TheAdmiester

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Jan 28, 2014
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Gsync works for all framerates the display is capable of displaying, even sub-30

What happens with GSync when you go over the refresh rate? Does it start going to half refresh rate to prevent tearing? E.G. if my monitor is 60Hz and I get 80, will it drop to 40Hz to prevent the tearing?

I do have a GSync monitor but have no idea about that part.
 

Sir Abacus

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What happens with GSync when you go over the refresh rate? Does it start going to half refresh rate to prevent tearing? E.G. if my monitor is 60Hz and I get 80, will it drop to 40Hz to prevent the tearing?

Gsync is Vsync on but with the frame being dispatched to the display as it's received.

The game won't (shouldn't) go over the framerate of the display.
 

McSpidey

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I'd love to see this in person since the framerate would seemingly have to be incredibly high (so only ancient games) for the temporal frame sampling to not introduce visible pacing issues/micro stutters. Though they hint at wanting to do something about that in the future too, perhaps motion compensated intermediate frames would help?
 

Demigod Mac

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This sounds great, but will it cause the GPU to render faster than the display like VSync OFF does, generating unnecessary workload/heat/energy consumption? (at least, for games that do not have an option to limit FPS)
 

AndyMoogle

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This sounds great, but will it cause the GPU to render faster than the display like VSync OFF does, generating unnecessary workload/heat/energy consumption? (at least, for games that do not have an option to limit FPS)

Yes. It's only really worth using when you can get well over 60fps in a game. For 60 fps and lower there will most likely be stutter introduced from this. Meaning that this tech is really not that great for demanding games or games that doesn't have an unlocked framerate.
 

ACH1LL3US

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It will still potentially lag because it has to synchronize the writing to the framebuffer and having it ready for vblank.

The engine may write into that buffer at any time within the 16.6ms between vblank. If it writes in the middle of that period you're getting 8ms lag, but if it writes toward the beginning you're getting mostly a frame of lag.


Right but a frame of lag is better then 4-5 frames of lag that vsync gives us :)
 

wildfire

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Jun 5, 2011
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It is called FAST Sync and what in laymans terms does is have vsync off and no tearing and just a smidge more input lag then just vsync off.

This is the common way people simplify this but after reading up on it it's essentially triple buffering supported at the driver level.

Seeing it as triple buffering gets across the strengths and weaknesses better than assuming vsync is off and it is pushing out frame as fast as possible.
 

ACH1LL3US

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This is the common way people simplify this but after reading up on it it's essentially triple buffering supported at the driver level.

Seeing it as triple buffering gets across the strengths and weaknesses better than assuming vsync is off and it is pushing out frame as fast as possible.


In that case, games like need for speed most wanted 2012 has triple buffered vsync, wouldnt using fast sync for a game reduce input lag and no tearing?
 

TSM

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Feb 15, 2014
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Fastsync isn't in any way comparable to gsync. Fastsync is still at the mercy of the scan rate of the monitor. Gsync will always scan out at your monitors highest refresh rate (generally 144hz) even if you are running under 30 fps. Fastsync still has to sync with your monitors refresh rate and really doesn't have tremendous benefits until you have extremely high in game frame rates. If you are internally rendering at 64fps and scanning out at 60 hz, then you will be unlikely to have any improvement over triple buffering. In fact if anything it seems like it's just driver level triple buffering, and you will have to have at least two times the frames as your refresh rate before you see 100% up time with fastsync. In other words the more your frame rate exceeds your refresh rate, the greater the impact of fastsync.

What hasn't been mentioned is that FastSync is only good for very high FPS situations where you run at least 2x your refresh rate, and will behave worse when FPS is lower or slightly above your refresh rate.

https://youtu.be/xtely2GDxhU?t=2h25m

Yeah, the Nvidia rep in this video says that it's not worth using if your fps isn't twice your refresh rate, and that running it at frame rates slightly above your refresh rate is actually worse than normal vsync.
 

Netherscourge

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Please keep in mind that Gsync is for under 60fps gaming and fast sync is for over 60fps gaming and does not require a special tv, monitor or input!!

I'm using G-sync right now at 75hz/75FPS
 

TheAdmiester

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Gsync is Vsync on but with the frame being dispatched to the display as it's received.

The game won't (shouldn't) go over the framerate of the display.

I thought it was that the monitor's refresh rate matches the framerate up to its max native refresh and down to 30, where it doubles the rate to match?
 

ACH1LL3US

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What option do we have at 60fps locked? I want lowr input lag and no tearing. Vsync on blows due to input lag.
 

TSM

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What option do we have at 60fps locked? I want lowr input lag and no tearing. Vsync on blows due to input lag.

If you can run at 120+ fps then fastsync is a real solution for you at 60hz. At some point between 60 and 120 fps fastsync should be better then vsync, but I'm not sure what number to recommend. Logic would seem to dictate that 90 fps should be the tipping point, but who knows in the real world. Basically this technology is only for people that play games that their video card can render at ridiculous frame rates or for people who don't care about latency and want driver level triple buffering.
 
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What hasn't been mentioned is that FastSync is only good for very high FPS situations where you run at least 2x your refresh rate, and will behave worse when FPS is lower or slightly above your refresh rate.

https://youtu.be/xtely2GDxhU?t=2h25m

Looks like it is going to introduce microstutter because of inconsistent frame pacing, maybe with a high refresh rate monitor it might not be noticeable because of the small time delta.
 

Swarna

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This sounds like you will just see the newest complete frame on each refresh of your display. Which isn't a new thing at all. I think the Windows Desktop on Windows 10 already does this. Some console games do this, too. But it's nice to have it as an explicit option in the driver.

Fast-sync can cause a juddering effect if your GPU fails to complete a new frame before the next refresh (resulting in a repeated frame similar to what happens in v-sync) or if the latest frame is very old in the refresh cycle (resulting in uneven motion of objects on the screen). Which is why, for example, a 60-70 FPS game on a 60hz can look janky.

Gsync is Vsync on but with the frame being dispatched to the display as it's received.

The game won't (shouldn't) go over the framerate of the display.

Behaviour for FPS over the refresh rate of the display just depends on your v-sync setting in Nvidia CP. It can use or not use v-sync like a regular monitor at that point. The default setting is v-sync on which is why you probably thought it locks your FPS.

Actually, it looks like you'll be able to use fast-sync as a third behaviour type for those situations now.
 

Gbraga

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With vsync off on sfv you get tearing, when using fast sync we wouldnt have tearing and the inout lag would still be seriously reduced!

Did anyone actually watch that video that I linked? Tom explains this is NOT triple buffering because triple buffering still has serious input lag!

I'm agreeing with you :p
 

Sir Abacus

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I thought it was that the monitor's refresh rate matches the framerate up to its max native refresh and down to 30, where it doubles the rate to match?

Yes. It does that by dispatching the frame to the display as soon as the frame completes rendering rather than waiting for VBLANK.
 

Sir Abacus

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Behaviour for FPS over the refresh rate of the display just depends on your v-sync setting in Nvidia CP. It can use or not use v-sync like a regular monitor at that point. The default setting is v-sync on which is why you probably thought it locks your FPS.

Oh they issued an update to the drivers it where it will render frames over the refresh rate. Initially when Gsync first came on the scene turning off vsync did absolutely nothing. Gsync will have the same latency as vsync off anyway so there was really no benefit apart from running the game logic faster. But once you're up at 144Hz on the game loop it really doesn't matter all that much from 200+ FPS.
 

TSM

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With vsync off on sfv you get tearing, when using fast sync we wouldnt have tearing and the inout lag would still be seriously reduced!

Did anyone actually watch that video that I linked? Tom explains this is NOT triple buffering because triple buffering still has serious input lag!

Did you watch the Nvidia presentation? It's literally driver based triple buffering. They have 3 buffers; a front buffer, a back buffer and a last rendered buffer:

https://youtu.be/WpUX8ZNkn2U?t=231

Also in this video the Nvidia rep specifically states that fastsync is worse than vsync at low to moderate framrates:

https://youtu.be/xtely2GDxhU?t=8727

This is specifically for people that are pushing games at 120+ fps with a 60hz display or with a 144hz display "running 200, 300, 350 frames per second" as the Nvidia rep said. "2 to 3 x is sort of the min" is what he said. so 120 to 180fps on a 60hz display.
 

dangerskew

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A friend of mine who's not a member wanted me to post this here:

here's a rundown of all the syncing methods that I think exist. latency means delay from your computer generating a frame, to your monitor displaying it.

NO SYNC AT ALL
facts:
system will make as many frames as possible
upsides:
lowest possible latency.
downsides:
if your system creates frames FASTER than your monitor can display them, your monitor will show parts of ALL of those frames. (tearing)
if your system creates frames SLOWER, it will feel like a lag spike, because the monitor will show the same image for at least 2 monitor refreshes.

GSYNC (the nvidia monitor one)
facts:
gsync is seperate from everything else. it can be turned on/off seperately, too.
upsides:
can lower (cannot increase) the refresh rate of your monitor to match the fps of a game you're playing. benifit is if your fps is below your monitor refresh rate, it will apear much smoother.
downsides:
requires compatible video card and compatible monitor
doesn't alwyas prevent screen tearing from happening.

FREESYNC (the AMD version of gsync)
facts:
does the exact same thing as gsync. except this requires a DIFFERENT set of compatible gpus/monitors
upsides from gsync:
cheaper for monitor manufacterers to impliment.
downsides from gsync:
because it's the cheaper option, GENERALLY they will be worse monitors. the lowest refresh rate won't be quite as low, etc.

VSYNC (the old one most people turn off)
facts:
there are many different kinds of vsync, but these up/downsides aply to all of them.
your system will cap framerate at your monitor's refreshrate
upsides:
no tearing!
keeps latency as consistant as possible. benificial for smoothest possible animations
downsides:
increases latency by at least the length of 1 frame. sometimes much much more.
doesn't do anything about the lag spike problem present with "NO SYNC AT ALL"

CAPPING FRAMERATE AT MONITOR REFRESH RATE
facts:
if you have gsync/freesync enabled, this is a very ideal choice.
upsides:
doing this without using vsync causes less latency.
no tearing! (maybe)
downsides:
doesn't do anything about the lag spike problem present with "NO SYNC AT ALL" (gsync takes care of it)
because it's difficult to cap at the exact refresh rate of your monitor, you may see 1 tear on your monitor that slooooowly moves, or you'll experience a lag spike every few moments. (as long as you cap BELOW monitor refresh rate, gsync will make it smooth)
doesn't manage frame pacing like vsync does, so latency could be anywhere between zero to one frame. (always as low as possible with gsync)

FAST SYNC (the new one that this thread is about)
facts:
doesn't cap framerate
this isn't like triple-buffering vsync, this works differently.
upsides:
no tearing!
very little delay (at LEAST less than 1 frame) this is because of a different method to handle rendered frames.
doesn't require any special monitor or TV! it'll work on any screen you can connect to your GPU.
downsides:
doesn't maintain frame pacing like vsync does, so not quite as smooth as vsync. becomes less of a problem as framerate gets higher.