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.



3233 Comments For “G-SYNC 101”

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TC.exe
Member
TC.exe

Howdy! Thanks a bunch for a fantastic write-up. I’m trying to use the information here to create a generalised flow-chart for myself and just wanted to clarify something. If the FPS exceeds the refresh rate, and there is not an in-game or config fps limiter, is Reflex (if available) the next optimal solution? Thanks

olly44444
Member
olly44444

Hi there,

I play competitive shooters and have been following the posts on g-sync settings. I’m curious if these results apply to freesync also? I have a 240hz freesync Alienware monitor. Currently the configuration I am using is ; Freesync on, rtss 237fps cap, v-sync on in radeon software. Is the v-sync going to pace the frames the same way as it would with g-sync? or is it going to add additional latency.

arshevizard
Member
arshevizard

I’m new to PC gaming and not a tech savvy person. Currently using 240hz monitor (MAG 271QPX QD-OLED E2) to play single player games in 1440P.

My FPS in games usually 90 – 120 depending on the game. Should I enable adaptive sync and Vsync and Gsync NVCP as well? Also, my monitor have option to turn on/off DSC. Should I use DSC?

jeffoo3
Member
jeffoo3

what if the game im playing is capped at like 60fps or 120fps?, do i cap my fps at 57 or 117 or do i just set my monitor hz to 60/120?

ez4angelo
Member
ez4angelo

Hey, a CS2 player here…
Recently steam give this give for optimizing the game and also starts as an notification on the game when you have GSYNC enabled on your monitor and NVCPL:
https://help.steampowered.com/en/faqs/view/418E-7A04-B0DA-9032

I would like to kindly ask, what would be the best settings? It seems that an in-game VSYNC and Reflex do the work pretty well, but, how about FPS Limiters and Low Latency Mode?

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