G-SYNC 101: G-SYNC vs. V-SYNC w/FPS Limit


So Close, Yet So Far Apart

On the subject of single, tear-free frame delivery, how does standalone double buffer V-SYNC compare to G-SYNC with the same framerate limit?

Blur Buster's G-SYNC 101: Input Latency & Optimal Settings
Blur Buster's G-SYNC 101: Input Latency & Optimal Settings
Blur Buster's G-SYNC 101: Input Latency & Optimal Settings
Blur Buster's G-SYNC 101: Input Latency & Optimal Settings
Blur Buster's G-SYNC 101: Input Latency & Optimal Settings
Blur Buster's G-SYNC 101: Input Latency & Optimal Settings

As the results show, but for 60Hz (remember, a “frame” of delay is relative to the refresh rate), the numbers are relatively close. So what’s so great about G-SYNC’s ability to adjust the refresh rate to the framerate, if the majority of added input latency with V-SYNC can be eliminated with a simple FPS limit? Well, as the title of this section hints, it’s not quite that cut and dry…

While it’s common knowledge that limiting the FPS below the refresh rate with V-SYNC prevents the over-queuing of frames, and thus majority of added input latency, it isn’t without its downsides.

Unlike G-SYNC, V-SYNC must attempt to time frame delivery to the fixed refresh rate of the display. If it misses a single one of these delivery windows below the maximum refresh rate, the current frame must repeat once until the next frame can be displayed, locking the framerate to half the refresh rate, causing stutter. If the framerate exceeds the maximum refresh rate, the display can’t keep up with frame output, as rendered frames over-queue in both buffers, and appearance of frames is delayed yet again, which is why an FPS limit is needed to prevent this in the first place.

When an FPS limit is set with V-SYNC, the times it can deliver frames per second is shrunk. If, for instance, the FPS limiter is set to 59 fps on a 60Hz display, instead of 60 frames being delivered per second, only 59 will be delivered, which means roughly every second a frame will repeat.

As the numbers show, while G-SYNC and V-SYNC averages are close over a period of frames, evident by the maximums, it eventually adds up, causing 1/2 to 1 frame of accumulative delay, as well as recurring stutter due to repeated frames. This is why it is recommended to set a V-SYNC FPS limit mere decimals below the refresh rate via external programs such as RTSS.

That said, an FPS limit is superior to no FPS limit with double buffer V-SYNC, so long as the framerate can be sustained above the refresh rate at all times. However, G-SYNC’s ability to adjust the refresh rate to the framerate eliminates this issue entirely, and, yet again, beats V-SYNC hands down.



1462 Comments For “G-SYNC 101”

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Sort by:   newest | oldest | most liked
BlackStorm82
Member
BlackStorm82

240Hz / GSYNC ON / 60FPS
240HZ / GSYNC OFF / 60FPS

Which is better in response time? Which one is better for blur?
G-Sync’s variable refresh rate function Does the screen response speed also affect it?

swaz
Member
swaz

Hi,
NVIDIA recently introduced a new “Max Frame Rate” setting in its Control Panel.
So I’m wondering if that uses the same FPS limiter tested via “Nvidia Inspector” on page 11.
If that’s not the case, when an in-game framerate limiter isn’t available, should I use RTSS or this new setting?
Thanks in advance.

DrGoku4star
Member
DrGoku4star

I’ve noticed more and more game now are ditching “Fullscreen exclusive” mode now such as Wow (World of warcraft) and Cod (Call of Duty) cold war and Rust.

One way i verify this is buy moving the volume scroll on my keyboard, and if i see the windows volume overlay appear in game, it’s not full screen exclusive?

Anyway, my main question is, with what i just said in mind, isn’t it better to leave The “Full screen optimizations” box ticked now? So that the DWM bypasses triple buffed v-sync?

Talos-LXIX
Member
Talos-LXIX

Hello there!
First i just want to say thank you so much for all the amazing work you guys do. in-depth analysis and guides like this are really helpful.

I just have a few things that I’m not entirely sure about.

1) You’ve found that G-SYNC completely bypasses the 1 frame of delay add by DWM in windowed/borderless. is that only the case if you’re within the G-SYNC range with V-SYNC enabled? could you still bypass it if you ran G-SYNC with V-SYNC off while being over your monitors refresh rate?

2) is G-SYNC+ V-SYNC off with fps over the monitors refresh rate identical to G-SYNC off + V-SYNC off?
For some reason some games (Apex Legends for example) lock their fps to my monitors refresh rate (120) when i try to disable G-SYNC via the per program settings on the NVCP.
I typically like to disable it for competitive FPS games as i can get much higher FPS than 120.

Hiram
Member
Hiram

Hello, I have read a lot, but I have a question.
In my case I play Fortnite, and if I limit the fps to 144 in the game and in the NVCP the screen tearing is not very noticeable, but it happens, otherwise if I play at limited 120 fps the screen tearing is much more noticeable, ( also putting 120hz in the NVCP).
Of course, my fps are not very stable when I get into a fight, they drop from 120 to 100 or a little less.
My question is, do I have to have V-sync activated?
I hope you can answer me

wpDiscuz