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.



2611 Comments For “G-SYNC 101”

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Alex UA6
Member
Alex UA6

Hey brother, sorry to bother you again but I’m confused about one thing so in the game I play insurgency sandstorm it does not support freesync or Gsync. So in game I have limited my frames to my monitors, refresh rate, and enabled Vsync so I don’t get screen tearing. If I disable Vsync it’s unbearable. If in a newer game like modern warfare 2 would I want Vsync disabled? Also, if there’s anything you can tell me about the set up for insurgency, please feel free to let me know.

tbowly
Member
tbowly

is this normal? i have 60 stable fps on my 165hz Gsync monitor but the refresh rate keeps changing and is not stable, it keeps changing constantly to 50-80Hz happens to all of my games, and when a game has like 80 fps it keeps changing to 60-100Hz

tbowly
Member
tbowly

here’s the video of my problem: https://streamable.com/mm3oun

mustardpapi
Member
mustardpapi

I have a XL2546 so it is not G sync compatible. Should I still utilize 236 fps while using DYAC + nvidia V sync? Or are these settings G sync specific?

Alex UA6
Member
Alex UA6

Hey brother, my buddy, just picked up an LG ultra gear 165hz monitor with adaptive sync. I’m a little confused with the word adaptive sync. Is it just another word for free sync or G sync? I’m trying to understand if I should enable V sync when using adaptive sync. On my free sync display I enable V sync to eliminate screen tearing.

BNThuan
Member
BNThuan

Hi. Im playing ” crossfire” with monitor 165 hz . I setted up G sync “on” +V sync “on”+ limited fps “162” but in game fps still from 199-200 and lag. I have already changed setting NVCP but that problem has not improved. please give me advice. thanks

Karambol2K
Member
Karambol2K

Where did you cap fps? In game or in nvidia panel? I personally recommend RTSS for capping frames.

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