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Nvidia Adaptive 1/2 Refresh V-sync + FPS cap

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Nvidia Adaptive 1/2 Refresh V-sync + FPS cap

Postby TripleM » 22 Jul 2018, 22:42

Hi,
I use Adaptive 1/2 Vsync on a 60Hz display so it limits FPS to 30 but the input lag is quite bothersome.

Now I know 30fps will always have input lag but that's what I gotta make do with atm with a 750ti. To help with this I use Inspector's Limiter V1 for a 30fps cap and it does help quite a bit in some games . The problem is, with a fps cap in place the Vsync never works correctly and it just seems to engage then disengage and is just jarring with screen tearing. The FPS are pretty solid at 30 with no drops but the tearing still persists.

Just wondering why does this occur. Adaptive Half Vsync limits fps to 30 anyway so a 30fps cap shouldn't cause any problems you'd think? Or maybe it's a driver issue on my side?
Any help's appreciated.

I only use Adaptive vsync for the games that don't have triple buffered vsync and I can't play with tearing. (i.e Assassin's creed 4, Just cause 3 etc)
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Re: Nvidia Adaptive 1/2 Refresh V-sync + FPS cap

Postby RealNC » 22 Jul 2018, 23:25

Instead of half refresh adaptive vsync, use non-adaptive 1/2 vsync and use RTSS to cap to half your true refresh rate minus 0.01. You can use Profile Inspector to set 1/2 vsync, since it's not settable in the nvidia panel.

As for RTSS, you can either use it stand-alone for its FPS limiter, or install it together with MSI Afterburner. If you're not interested in the OSD statistics of Afterburner, you can just install RTSS on its own.

This is needed because the NVidia limiter adds one frame of input lag, and at 30FPS that's too much (33ms more lag compared to RTSS.)

Make sure to download the most recent beta of RTSS in order to be able to set a fractional FPS cap in the GUI. You need at least RTSS 7.2.0 Beta 2 from here:

https://www.guru3d.com/files-details/rt ... nload.html

Follow the steps here to find out your true refresh rate and set the cap in RTSS:

https://forums.guru3d.com/threads/the-t ... st-5380262

Note that in your case, you must cap to Hz / 2 - 0.01. For example, if your refresh rate is 59.94Hz, you need to cap to 29.96FPS

It could be that setting "1/2 vsync" in inspector won't apply without a reboot, and it might not work in some cases (like Doom 4.) To verify this, you can run the game without an FPS cap (set "0" as the cap in RTSS) and see if the game runs at 30FPS. If not, 1/2 vsync didn't work. Try to reboot.
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Re: Nvidia Adaptive 1/2 Refresh V-sync + FPS cap

Postby TripleM » 23 Jul 2018, 01:06

RealNC wrote:Instead of half refresh adaptive vsync, use non-adaptive 1/2 vsync and use RTSS to cap to half your true refresh rate minus 0.01. You can use Profile Inspector to set 1/2 vsync, since it's not settable in the nvidia panel.


First off, thanks a bunch for all the info mate. Will definitely be trying out the -0.01 technique in a while.
As for the non-adaptive 1/2 vsync, looking back at my post guess I should have been a bit clearer about it, sorry about that.

I already use that in most of my demanding games the non-adaptive 1/2 vsync with Fps cap and it works wonderfully. But some games don't offer triple buffered vsync so using this method whenever the gpu hits 90% usage the frames get locked at 20. Trying to workaround this I found adaptive 1/2 vsync is the only solution and fps remain solid at 30 but with higher than normal input lag. Locking fps at 30 improves the lag but causes screen tears with adaptive vsync.

So was just wondering with adaptive half VSYNC enabled (without a cap) fps are locked at 30 and applying a 30fps cap they are still at 30 of course but now vsync would not work.
Again thanks for the reply.
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Re: Nvidia Adaptive 1/2 Refresh V-sync + FPS cap

Postby RealNC » 23 Jul 2018, 05:42

Triple bufferred vsync at 30FPS is a bad idea anyway.

There's no magic bullet, I'm afraid. If even 30FPS is too much, you need a faster system :-/
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Re: Nvidia Adaptive 1/2 Refresh V-sync + FPS cap

Postby TripleM » 23 Jul 2018, 06:23

Yeah I feared as much.
Well thanks anyway.
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