Tearing, VSync, Fast Sync, GSync, Freesync – Rocket Science #9
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Tearing, VSync, Fast Sync, GSync, Freesync – Rocket Science #9

January 19, 2020


Hey Guys,
HalfwayDead here. In this video I’m going to try and explain
Tearing, what causes it and what exactly VSync, GSync, Freesync and FastSync do to stop it
and how they differ. If you’re not a Rocket League player don’t
worry. This video has some Rocket League footage
as examples but everything I’m going to say stays true for other games. Just a quick note on the side. I’ve uploaded another video today with a big
announcement, so make sure to check that out. So what is tearing? Tearing is what you should see on screen right
now. Can’t see it? Ok let’s pause. This horizontal line on screen is a tear. It means you’re seeing the top half of one
frame and the bottom half of the next frame at the same time. You might already be used to it but it’s a
visual artifact that is definitely unwanted. So why does that happen when you game? For that I need to explain some of the basics
of how the monitor and graphics card work together. In order for the monitor to know what it’s
supposed to display, the graphics card keeps a constant copy of the current image in a
part of it’s memory. The so called front buffer. All the monitor does, is read from the front
buffer, pixel by pixel, line by line, frame by frame. The so called refreshrate is just the amount
of full frame cycles that the monitor goes through every second. Alright so far, but for games we don’t want
to display a static image but an updated one as often as possible. For that the GPU renders new images in the
back buffer. Whenever a frame is done rendering the graphics
card will do a page flip. The 2 buffers are in reality identical and
all that’s done in a page flip is flip the definition of the buffers. And here we see the problem. The monitor just keeps on reading what is
considered the front buffer and starts getting a new frame in the middle of the screen. And unlike what a lot of people claim on the
internet, this can obviously happen at any framerate. If the framerate is half of the refreshrate
then there will be one tear every second frame. If it is twice the refreshrate then you’ll
have 2 tears on every frame. This may sound like high framerates make the
problem worse but in a game that is not true, because if you’re outputting more frames per
second, then everything moves less between the frames so each tear is less noticeable. But what about eliminating tears altogether? For that there is VSync. The way it works is pretty simple. Instead of instantly doing a page flip once
a frame is done rendering, the graphics card waits. The monitor then sends a VSync signal once
it reached the end of a full refresh, allowing the page flip to happen at just the right
time. Sounds great, but for gaming there are a couple
of problems with this approach. The graphics card is waiting on the monitor
and the processor is then waiting on the graphics card. This forces the entire pipeline to slow down
causing input lag. How much exactly that is in Rocket League
is something that I’ll test in a future video for which I’ve bought a highspeed camera. Additionally to the lag, when your computer
just takes a tiny bit too long to render a frame then the monitor will display the previous
frame for an entire new refresh cycle. That means you’re trading a major stutter
for a tear. So pick your poison. To solve the input lag problem there is NVIDIA
FastSync. It introduces a second back buffer. This allows the GPU to alternate between the
two back buffers for rendering, never needing to slow down. Whenever the monitor finishes a refresh, the
front buffer will then switch with the newest finished image. However, this still does nothing about the
stuttering issues and if you have the ball stuttering around in Rocket League then that
could hinder you from estimating it’s speed or trajectory, making FastSync only really
viable if you get really high framerates. And at that point you gotta ask yourself if
you can even notice the tearing. That leaves us with GSync or what is essentially
the same idea for AMD cards, Freesync. They do the opposite of VSync. Instead of letting the GPU wait for the monitor,
the monitor waits for new frames from the GPU. So it only starts reading from the front buffer
if a new frame is available. This means: No tearing, no added input lag
and less stuttering when you get unstable framerates. So there is only 1 minor issue with this technology. Since the system is relying on the monitor
to wait for the graphics card, the monitor needs to be capable of displaying more frames
than the graphics card puts out. This can be forced by capping the framerate
below the refreshrate but as I said in my input lag video, the more frames per second
you have, the less input lag you’ll have. For more information on how to set up GSync
perfectly I recommend reading the excellent blurbusters articles, which I’ll put in the
video description. So these are all the options you have. I personally am playing 250FPS with VSync
off because I don’t notice any tearing with that and it gives me the lowest input lag. For Rocket League though the perfect setup
would most likely be one of the 240Hz GSync or Freesync displays with the framerate capped
to 237. The difference in input lag would be neglible
and it would prevent all tearing. And it’s a better experience in case of FPS
drops. However, the price for GSync displays is very
high so that is not an option for many. Alright, if you haven’t watched my announcement
yet then I recommend you do that now. I’ve created a Patreon and with a small pledge
you can help in allowing me to make these videos on the regular and you’ll get some
small benefits from it in return. So go check that out, follow my twitter and
I’ll see you in 2 weeks for the next video.

Only registered users can comment.

  1. Sorry for the delay. The individual pixels on the screen seemed to take forever to render.
    Before anyone complains, yes, the animations are oversimplified but that is irrelevant for any of the discussed points and simple is easier to understand.

  2. Can you figure out how much input lag there is on console with vsync off? I tried to make the switch to pc but I was only getting 65 fps max and the input lag made me play way worse compared to console. I am currently upgrading my monitor and pc to be able to run the game at 144 fps at least

  3. What do you think is the best FPS setting in game for a 165hz monitor? 162? Also, I have a G-Sync 165hz 1440p monitor, but I turn G-sync off because it makes the monitor REALLY hot, and it being a $700 monitor, I'd like it to last a long time so…. and I barely notice a difference with G-sync off anyways

  4. hey ๐Ÿ™‚ can you make a Video about the nvidia 3d Settings because they are very important and maybe it helps to understand some Things ๐Ÿ™‚ thx you and Keep it up !

  5. What about vsync on but capping frame rate to one below the monitors refresh rate? I read in a post that this will reduce input lag since vsync is processing the exact amount of frames, taking into account the one frame buffer.

  6. I have an asus rog swift pq248q with gsyns how to proper set it up for rocket league? I run it at 144 hz not 160 which is the limit

  7. I have no clue what's wrong with my set up now. I have a GTX 1060 6GB with a 4k monitor that have 4ms, and 60hz. Rocket league plays better on my 1080p 144hz 1ms. Game says it's getting over 100fps on the 4k but I can see that it's not, feels more like 35 or 45. sometimes I can tell it's getting 60fps but most of the time it's not.

  8. @Rocket Science i hav a gsync monitor with 4k and 60 hz. i had some problems maby because i hav really low spec pc unil fast sync came out, but now the vertical tearing doesnt show ingame but in every youtube or netfix video so i messed around with the contol pannel setting and did literaly every fix i could find, but still no soulution to that. anyone can help me with that ?

  9. dude, this just the video i was looking for! nice presentation ๐Ÿ™‚ youtube recommendation while I was watching another vid on this topic.

  10. I was just curious about in game frame rate capping. Like in rocket league we can cap fps too. Does that solve tearing?

  11. Sorry, I find this a bit confusing.
    I have a nice 144hz monitor that can run freesync but I have an nvidia card gtx 680 from 2013 which is a bit old now and I want to upgrade soon.

    Question 1
    For now, if I play a more demanding game and only get 60 fps, from your video it sounds like it's better to turn vsync on, because in vsync the gpu is waiting on the monitor, but since my monitor is fast this is not as much of an issue because it won't be waiting long.

    However if I play a less demanding game like Rocket league or an old game like Call of Duty 4 and can get 180+ fps then I should turn vsync off or not?

    Question 2
    Lastly if I upgrade I guess I need to buy an amd video card to go with the monitor? Or is fast sync with the new nvidias enough? They seem expensive now in comparison for the same benchmark.

  12. I have a 240hz 1ms freesync monitor and I WILL use freesync and cap my frames at 237 ๐Ÿ˜ I hope I interpreted that correctly! I wonder if squishy uses free or g snyc ๐Ÿค” he keeps his frames at 250..

  13. LOL what am i doing in your Video? (FaaB) ๐Ÿ˜€ Damn, i didnt recorgnize that in the past when i saw the video xD

  14. I've been looking my hardest for the cheapest build suggestion for 144 frame gaming w/o compromising any input lag or tearing

  15. I have a 240hz monitor, recently got into RL on PC, set it to 237fps ingame last week before watching this video and set NVCP to Gsync + Vsync on, and now your video has confirmed that I did the right thing, pat on the back to me!

  16. I was experiencing tearing with some games. I turned V sync in the game off and turned it on in the nvidia control panel. Games run smoothly and perfectly now.

  17. PLEASE HELP
    I get screen tearing with vsync on and without theres no solution I tried everything. I use a TV as a monitor not sure if that is a problem

  18. I get screen tare on a 165hz monitor while playing 165fps even when I go down to 144fps on fortnite still I get screen tare and I
    Don't want to have to keep vsync on because there's input lag with vsync

  19. Good video, i really liked it. But I got a question: People seem to be fighting about turning VSync off and instead limiting the FPS to about the monitors refresh rate (i.e. via Riva Tuner). Some people say it solves all problems others say it's idiotic… How is your opinion on this?

  20. you showed a game throughout the entire time, rather than a table of recommendations which would have been MUCH better

  21. I have a Ryzen 3600 CPU, Asus GeForce RTX 2060 OC, Samsung 970 EVO Plus M.2 SSD, 16GB Corsair Vengeance DDR4 RAM and a Asrock b450m Steel Legend
    motherboard, paired with a AOC 2590 24.5" 144Hz G-Sync monitor.
    I get this nasty tearing in Rocket League, and I can't seem to get rid of it. Tried a bunch of things, nothing changes this issue.

  22. so fast sync would be best for me because im going for a higher fps than hz monitor sadly – budget gaming lol – but will be upgrading over the years XD

  23. Amazingly well done video. There are so many other videos out there with terrible or confusing information. This was great.

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