I found how to remove the automatic frame cap from gsync+vsync+reflex/ullm

Talk about NVIDIA G-SYNC, a variable refresh rate (VRR) technology. G-SYNC eliminates stutters, tearing, and reduces input lag. List of G-SYNC Monitors.
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Gamesager
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I found how to remove the automatic frame cap from gsync+vsync+reflex/ullm

Post by Gamesager » 02 Apr 2025, 16:19

Hi so I was trying to figure this out for a while and stumbled on this by accident while trying different settings for halo infinite.
Using nvidia profile inspector, all you need to do
  • Set Vsync to 1/4
    Set Vsync - Behavior Flags to 0x00000003.
    Make sure gsync is on in your nvidia control panel and you HAVE to have variable refresh rate set to on in windows graphics settings.
For some reason this removes the automatic frame caps while making the gsync vsync combo work.
You can test its working with rtss. Some games it wont work because it disables VRR for them, so if someone knows any ideas to make VRR work in the games that it disables it in, then we could get this to work in every game.
Doing this for halo and then setting the frame cap myself makes the game feel much better than the auto 225 cap on my 240 hz.

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Re: I found how to remove the automatic frame cap from gsync+vsync+reflex/ullm

Post by Chief Blur Buster » 03 Apr 2025, 00:07

Easier trick: Set the Halo cap to about 220-224, below the driver-based 225.

The latency ladder is:

- (Highest Lag) VSYNC-based hardware capping
- (In-Between Lag) Driver-based software capping
- (Lowest lag) Game-based software capping

So if you're using Reflex/ULLM, you can also use an in-game cap slightly below the Reflex/ULLM cap, to gain the low-latency benefits (without using Reflex/ULLM benefits for too-fast frametimes).
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Gamesager
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Re: I found how to remove the automatic frame cap from gsync+vsync+reflex/ullm

Post by Gamesager » 03 Apr 2025, 11:57

Chief Blur Buster wrote:
03 Apr 2025, 00:07
Easier trick: Set the Halo cap to about 220-224, below the driver-based 225.

The latency ladder is:

- (Highest Lag) VSYNC-based hardware capping
- (In-Between Lag) Driver-based software capping
- (Lowest lag) Game-based software capping

So if you're using Reflex/ULLM, you can also use an in-game cap slightly below the Reflex/ULLM cap, to gain the low-latency benefits (without using Reflex/ULLM benefits for too-fast frametimes).
Yeah, the point of this was just to get back up to the 237 cap instead of 225. For halo I am using rtss reflex cap set to 237 with the in game minimum frame rate set above that and it feels much better than the auto cap for me at least.

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Re: I found how to remove the automatic frame cap from gsync+vsync+reflex/ullm

Post by jorimt » 03 Apr 2025, 15:00

Gamesager wrote:
02 Apr 2025, 16:19
Another way to prevent the Reflex auto limiter from engaging in some games is to simply use G-SYNC + in-game V-SYNC instead of G-SYNC + NVCP V-SYNC.
(jorimt: /jor-uhm-tee/)
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Re: I found how to remove the automatic frame cap from gsync+vsync+reflex/ullm

Post by Chief Blur Buster » 03 Apr 2025, 18:59

Gamesager wrote:
03 Apr 2025, 11:57
Yeah, the point of this was just to get back up to the 237 cap instead of 225. For halo I am using rtss reflex cap set to 237 with the in game minimum frame rate set above that and it feels much better than the auto cap for me at least.
Yes, the Reflex/ULLM cap is pretty conservative.

You can use tighter capping for extremely-accurate framepacing (e.g. just 1% below) or looser capping for looser framepacing (e.g. 5% below). The problem is framepacing is jittered by many things, even by things like power management.

That said, if you use the same capping mechansim (e.g. in-game capping mechanism, or external driver/RTSS-based capping mechanism)

It is the latency differential of the shortest frametimes. (1/225)-(1/237) = 0.23ms difference. Assuming average lag (top/center/bottom lags: Screen center instead of worst-case bottom-of-screen-edge lag), screen center is halftime (0.5/0.23ms) = ~0.1ms difference!

There's bigger latency differences between different capping mechanisms (e.g. internal vs external) than there is with these capping numbers (assuming using same capping mechanism). In this case, you've usually got one full refreshtime of lag differential; gigantic compared to the cap-number differences.

Nice to optimize both though (switch to internal capping mechanism + higher cap if possible); just that if you could only target ONE optimization -- choose a lower in-game cap switches the capping mechanism from the laggier external cap to a less laggy internal cap.

Yes, Reflex/ULLM is higher lag than an in-game cap, but it's lower lag than the worse (GSYNC turning into VSYNC ON because your framerate went too high), thanks to the latency ladder. It's lovely having Reflex/ULLM because lots of games don't let you do an in-game framerate cap; but an in-game framerate cap is usually lower lag than any external capping mechanism.
Chief Blur Buster wrote:The latency ladder is:

- (Highest Lag) VSYNC-based hardware capping
- (In-Between Lag) Driver-based software capping
- (Lowest lag) Game-based software capping
More about the two-cap technique; which is not commonly used by most of us;

If in-game framerate caps are only best-effort approximations and very jittery in frametimes (e.g. 220fps in-game cap jitters badly from 1/200sec to 1/240sec frametimes) -- Then it can overlap too frequently with the laggy external cap (being used as the fallback) and create weird lagfeel issues. So you need a safety margin between the internal in-game cap and the external framerate cap, to prevent weirdnesses.

External frame rate caps are usually much more glassfloor (especially RTSS-based frame rate caps). So the two-cap method can (instead of lag improvements) be used as motion fluidity improvements in certain stuttery games, where an in-game cap marginally lower than an external cap. The in-game cap is the low-lag one, and the external cap is the low-stutter one, so in things like emulator situations (e.g. 60fps GSYNC during 240Hz VRR), sometimes a 60fps emulator cap and a 61fps G-SYNC cap, can make RetroArch run much more smoothly in very stuttery emulator modules. So that's ANOTHER use case of the dual-cap method...

Also see "latency guard" in-game cap + "stutter guard" external cap, sometimes used to smooth-out framegen while making framegen a bit lower latency. That's for non-latency-critical non-esports use cases where you want lower framegen lag AND lower stutters (without worrying about the lowest-possible lag). It also helps some games that don't seem to do "VSYNC ON" properly, can sometimes framepace beautifully with this weird trick.

Obviously I'm just covering all the bases of all the weird ways to do the "two caps" tricks -- very niche tweak as it is.
Head of Blur Busters - BlurBusters.com | TestUFO.com | Follow @BlurBusters on: BlueSky | Twitter | Facebook

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  2. Please report rule violations If you see a post that violates forum rules, then report the post.
  3. ALWAYS respect indie testers here. See how indies are bootstrapping Blur Busters research!

Gamesager
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Re: I found how to remove the automatic frame cap from gsync+vsync+reflex/ullm

Post by Gamesager » 06 Apr 2025, 21:04

Chief Blur Buster wrote:
03 Apr 2025, 18:59
Gamesager wrote:
03 Apr 2025, 11:57
Yeah, the point of this was just to get back up to the 237 cap instead of 225. For halo I am using rtss reflex cap set to 237 with the in game minimum frame rate set above that and it feels much better than the auto cap for me at least.
Yes, the Reflex/ULLM cap is pretty conservative.

You can use tighter capping for extremely-accurate framepacing (e.g. just 1% below) or looser capping for looser framepacing (e.g. 5% below). The problem is framepacing is jittered by many things, even by things like power management.

That said, if you use the same capping mechansim (e.g. in-game capping mechanism, or external driver/RTSS-based capping mechanism)

It is the latency differential of the shortest frametimes. (1/225)-(1/237) = 0.23ms difference. Assuming average lag (top/center/bottom lags: Screen center instead of worst-case bottom-of-screen-edge lag), screen center is halftime (0.5/0.23ms) = ~0.1ms difference!

There's bigger latency differences between different capping mechanisms (e.g. internal vs external) than there is with these capping numbers (assuming using same capping mechanism). In this case, you've usually got one full refreshtime of lag differential; gigantic compared to the cap-number differences.

Nice to optimize both though (switch to internal capping mechanism + higher cap if possible); just that if you could only target ONE optimization -- choose a lower in-game cap switches the capping mechanism from the laggier external cap to a less laggy internal cap.

Yes, Reflex/ULLM is higher lag than an in-game cap, but it's lower lag than the worse (GSYNC turning into VSYNC ON because your framerate went too high), thanks to the latency ladder. It's lovely having Reflex/ULLM because lots of games don't let you do an in-game framerate cap; but an in-game framerate cap is usually lower lag than any external capping mechanism.
Chief Blur Buster wrote:The latency ladder is:

- (Highest Lag) VSYNC-based hardware capping
- (In-Between Lag) Driver-based software capping
- (Lowest lag) Game-based software capping
More about the two-cap technique; which is not commonly used by most of us;

If in-game framerate caps are only best-effort approximations and very jittery in frametimes (e.g. 220fps in-game cap jitters badly from 1/200sec to 1/240sec frametimes) -- Then it can overlap too frequently with the laggy external cap (being used as the fallback) and create weird lagfeel issues. So you need a safety margin between the internal in-game cap and the external framerate cap, to prevent weirdnesses.

External frame rate caps are usually much more glassfloor (especially RTSS-based frame rate caps). So the two-cap method can (instead of lag improvements) be used as motion fluidity improvements in certain stuttery games, where an in-game cap marginally lower than an external cap. The in-game cap is the low-lag one, and the external cap is the low-stutter one, so in things like emulator situations (e.g. 60fps GSYNC during 240Hz VRR), sometimes a 60fps emulator cap and a 61fps G-SYNC cap, can make RetroArch run much more smoothly in very stuttery emulator modules. So that's ANOTHER use case of the dual-cap method...

Also see "latency guard" in-game cap + "stutter guard" external cap, sometimes used to smooth-out framegen while making framegen a bit lower latency. That's for non-latency-critical non-esports use cases where you want lower framegen lag AND lower stutters (without worrying about the lowest-possible lag). It also helps some games that don't seem to do "VSYNC ON" properly, can sometimes framepace beautifully with this weird trick.

Obviously I'm just covering all the bases of all the weird ways to do the "two caps" tricks -- very niche tweak as it is.
So rtss presentmon overlays both show my latency lower with the rtss reflex cap on vs in game frame cap. And it does feel lower for me as well. Is it 100% that the reflex rtss cap always has you a refresh cycle behind and present mon isnt able to measure this accurately? Its kind of strange to explain, but Its not actually the 2 cap I am using. Halo has a minimum frame rate you can change to be higher in the config which is dynamic scaling resolution basically. I set that to 260 and then external cap to 237. So it completely locks me to 237 and gives me almost perfect 1% lows. Even my 0.1% lows are usually 237 set this way. You cant do this using the in game cap since the in game has to be same or lower than the minimum. But say I have it set to 237 and cap 237, that introduces a lot of lag, but having it set higher and external capping lower just makes it run perfectly smooth.

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