V-sync at 60hz is better than 75hz for me. Is this right?

[Zeze]

Long story short, I upgraded my rig with gtx 1060 6gb with i7-3770. And my 60 hz monitor can be OC'd to 75hz.

When playing Doom with max settings at 1080p, I have noticed that it's less laggy at 60hz refresh rate than 75hz.

I think I know why. Please let me know if my assumption is correct or I'm imagining this.

The game hovers around 70-90 fps (without vsync). When action gets intense, it even gets to 50-60's.

When using 75hz refresh rate, the framerate dips to below 75fps too often, then per v-sync's rule, it dips to the next half rate which is 37fps.

But if I'm sticking with 60hz refresh rate, the threshold of dipping to the half rate is lower at 60fps. Therefore it maintains 60 fps when at 75hz, it would've dipped to 37fps.

Is my speculation correct? The game does seem to run smoother at 60hz.

 

[Headfoot]

Since you've got a 1060, I would skip the vsync no vsync debate here altogether and use the nVidia Adaptive Sync feature, which is basically a better vsync: https://www.geforce.com/hardware/technology/adaptive-vsync for this exact kind of situation

 

[richaron]

When using 75hz refresh rate, the framerate dips to below 75fps too often, then per v-sync's rule, it dips to the next half rate which is 37fps.

But if I'm sticking with 60hz refresh rate, the threshold of dipping to the half rate is lower at 60fps. Therefore it maintains 60 fps when at 75hz, it would've dipped to 37fps.

Is my speculation correct? The game does seem to run smoother at 60hz.

This is the first time I've heard anyone claim vsync will half refresh rates. I suspect you're confusing a different frame rate technology.

I'd rather have higher fps (and less input lag) more of the time so I'd run 75fps without question. The only reason to run otherwise would be if you are insanely susceptible to tearing or frame rate variance, which could be less of a problem at 60Hz. But by that logic tearing and frame variance will probably be better at 30fps so why not just do that instead? Either way it's nothing like your reasoning of 37fps vs 60fps.

Edit: I'm happy to learn more. So it would be nice if anyone would like to illuminate me/us about the "half" fps thing. Pondering about a worst case situation I think I can see the claim (wrt single/double/triple buffer), but halving fps still seems unlikely in reality.

 

[Tup3x]

If it feels smoother at 60Hz then 75Hz then there's a chance that your display is actually dropping frames when you run it at 75Hz. Massive majority doesn't do that but there are displays that do.

If you don't want to halve your FPS when the game doesn't hit 75Hz either enable triple buffering (force from driver) or use adaptive v-sync.

 

[Prey2big]

OP answered his own question.

 

[bystander36]

This is the first time I've heard anyone claim vsync will half refresh rates. I suspect you're confusing a different frame rate technology.

I'd rather have higher fps (and less input lag) more of the time so I'd run 75fps without question. The only reason to run otherwise would be if you are insanely susceptible to tearing or frame rate variance, which could be less of a problem at 60Hz. But by that logic tearing and frame variance will probably be better at 30fps so why not just do that instead? Either way it's nothing like your reasoning of 37fps vs 60fps.

Edit: I'm happy to learn more. So it would be nice if anyone would like to illuminate me/us about the "half" fps thing. Pondering about a worst case situation I think I can see the claim (wrt single/double/triple buffer), but halving fps still seems unlikely in reality.

Most games use a double buffering system. That means that there is a buffer the game creates frames on, and another which is used by the monitor to display the last finished frame. Because it takes time to display the image on the screen, the monitor needs a frame that is not being altered, or you'll get tearing and other artifacts. Be aware that SLI and CF will automatically create an extra buffer for each additional GPU, which will prevent the following explanation from happening.

With V-sync, the GPU prevents frames from being sent to the front buffer (the one the display uses to display images), if the monitor is not in vertical blanking mode, this happens between image updates to the display, and at 60hz, it happens every 16.7ms. If the display is not in vertical blanking mode, the GPU waits until it is. This is the key to half FPS.

In a double buffering system, the front buffer holds the last completed image waiting to be displayed, and the back buffer holds the currently worked on, and potentially finished image that is waiting to be sent to the front buffer. Once finished, the GPU cannot work on a new frame until it is sent to the front buffer to be displayed and it cannot send it to the front buffer until the image in the front buffer has been displayed by the monitor. While waiting, the GPU sits idle.

The big problem with the double buffering system and V-sync, is when frames are generated slightly slower than 16.7ms. Let's say it takes 17ms to create an image, which might results in 55-59 FPS without V-sync on. The frame was 1st being worked on, just after the last image was displayed during vertical blanking mode. Vertical blanking mode comes around 16.7ms later, but the GPU is spending 17ms to create an image, so it misses the opportunity to send a new image and has to wait for the next vertical blanking mode 16.7ms later, which adds up to 33.3ms later (30 FPS). Because the GPU cannot work on a new frame until the current one is sent to the front buffer, it sits idle until that next vertical blanking mode. Once it finally does send it, it works on a new frame, and if it continues to take 17ms to create a new frame, the same thing happens again, resulting in 30 FPS over a long period of time.

Triple buffering fixes this problem, but causes another problem with latency, so most dev's do not use triple buffering.

 

[Ferzerp]

The first reply had the right answer.

 

[richaron]

Most games use a double buffering system. That means that there is a buffer the game creates frames on, and another which is used by the monitor to display the last finished frame. Because it takes time to display the image on the screen, the monitor needs a frame that is not being altered, or you'll get tearing and other artifacts. Be aware that SLI and CF will automatically create an extra buffer for each additional GPU, which will prevent the following explanation from happening.

With V-sync, the GPU prevents frames from being sent to the front buffer (the one the display uses to display images), if the monitor is not in vertical blanking mode, this happens between image updates to the display, and at 60hz, it happens every 16.7ms. If the display is not in vertical blanking mode, the GPU waits until it is. This is the key to half FPS.

In a double buffering system, the front buffer holds the last completed image waiting to be displayed, and the back buffer holds the currently worked on, and potentially finished image that is waiting to be sent to the front buffer. Once finished, the GPU cannot work on a new frame until it is sent to the front buffer to be displayed and it cannot send it to the front buffer until the image in the front buffer has been displayed by the monitor. While waiting, the GPU sits idle.

The big problem with the double buffering system and V-sync, is when frames are generated slightly slower than 16.7ms. Let's say it takes 17ms to create an image, which might results in 55-59 FPS without V-sync on. The frame was 1st being worked on, just after the last image was displayed during vertical blanking mode. Vertical blanking mode comes around 16.7ms later, but the GPU is spending 17ms to create an image, so it misses the opportunity to send a new image and has to wait for the next vertical blanking mode 16.7ms later, which adds up to 33.3ms later (30 FPS). Because the GPU cannot work on a new frame until the current one is sent to the front buffer, it sits idle until that next vertical blanking mode. Once it finally does send it, it works on a new frame, and if it continues to take 17ms to create a new frame, the same thing happens again, resulting in 30 FPS over a long period of time.

Triple buffering fixes this problem, but causes another problem with latency, so most dev's do not use triple buffering.

Thanks for taking the time to expand, very helpful.

I knew a little about the subject and OP's talk of halving frame rates seemed off to me, but now I see rather than an exact halving fps by design it's more of a worst case scenario thing. Still I opened my cake-hole without knowing the full story so I guess I'm now one of "those guys" :/