G-sync only feels smooth when I have a twitch stream in the background. What gives?

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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actualthroway
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G-sync only feels smooth when I have a twitch stream in the background. What gives?

Post by actualthroway » 10 Aug 2020, 10:30

G-sync only seems to work when I have a Twitch stream in the background.

I found this out by chance when I opened up a Twitch stream and decided to directly alt-tab back to the game I was playing with the twitch stream as the primary tab in chrome and I had noticed that everything became remarkably smooth, even games that were locked to 60 fps started feeling almost like 144fps (almost). My monitor is the Dell s2716dg. What confuses is me is that the "G-sync On" indicator is always visible regardless of whether I have a twitch stream in the background or not, yet games look objectively smoother to me when I have a twitch stream on.




What could be the reasoning for this?

My system specs are as follows:
Intel 5820k overclocked at 4.4Ghz 1.295 volts
Corsair 16gb ram at 2666 with timings of 16-18-18-35 at 1.25 volts
EVGA 1080 GPU at factory overclock
Windows 8.1 64 bit
Dell s2716dg
My Nvidia Driver is 445.75
SSDs only

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jorimt
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Re: G-sync only feels smooth when I have a twitch stream in the background. What gives?

Post by jorimt » 10 Aug 2020, 13:29

actualthroway wrote:
10 Aug 2020, 10:30
G-sync only seems to work when I have a Twitch stream in the background.

I found this out by chance when I opened up a Twitch stream and decided to directly alt-tab back to the game I was playing with the twitch stream as the primary tab in chrome and I had noticed that everything became remarkably smooth, even games that were locked to 60 fps started feeling almost like 144fps (almost). My monitor is the Dell s2716dg. What confuses is me is that the "G-sync On" indicator is always visible regardless of whether I have a twitch stream in the background or not, yet games look objectively smoother to me when I have a twitch stream on.




What could be the reasoning for this?
Hard to say without testing in person, but it seems less like a direct G-SYNC issue, and more due to system performance...

Having another program open in the background is possibly forcing your system to use more of its capability, upping CPU/GPU clocks (and/or other performance metrics) and increasing overall component usage in the process, thus improving overall frametime performance, which, in turn, is indirectly affecting perceived G-SYNC fluidity (as it merely mirrors the system).

This would vary by how much (and how) the given game engine pushes the system when running on its own though. I would guess this would be more evident in game engines that don't push the system very hard (older titles), or have lots of internal software bottlenecks (poor optimization).

The only time I personally noticed this phenomena, was years ago where I had a browser open in the background when playing the original State of Decay, which would stutter more if I had nothing running in the background. That game did have very poor optimization though.
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Re: G-sync only feels smooth when I have a twitch stream in the background. What gives?

Post by Chief Blur Buster » 11 Aug 2020, 19:46

Power management interferes with VRR framepacing, because VRR performs best with sub-millisecond-accurate "gametime:photontime" sync.

Games capped to 60fps, utilize a very low percentage of the GPU, which can trigger the GPU into power management, creating framepacing accuracies that forces divergences between gametime (the game's internal perception of time) and photontime (the photons hitting eyeballs).
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       To support Blur Busters:
       • Official List of Best Gaming Monitors
       • List of G-SYNC Monitors
       • List of FreeSync Monitors
       • List of Ultrawide Monitors

actualthroway
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Joined: 25 Mar 2020, 14:05

Re: G-sync only feels smooth when I have a twitch stream in the background. What gives?

Post by actualthroway » 13 Aug 2020, 13:32

Chief Blur Buster wrote:
11 Aug 2020, 19:46
Power management interferes with VRR framepacing, because VRR performs best with sub-millisecond-accurate "gametime:photontime" sync.

Games capped to 60fps, utilize a very low percentage of the GPU, which can trigger the GPU into power management, creating framepacing accuracies that forces divergences between gametime (the game's internal perception of time) and photontime (the photons hitting eyeballs).
What about for games that run uncapped and around 144fps? The "fix" still makes a difference in smoothness for me in those games and I usually have 30-70% GPU in most games I play. Could my GPU be running in power management mode despite me having it disabled in the control panel?

MT_
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Re: G-sync only feels smooth when I have a twitch stream in the background. What gives?

Post by MT_ » 20 Aug 2020, 17:15

For smoothest possible gameplay a few key factors are indeed very important:

- Forced maximum clocks on CPU/GPU while in game. (Either through speedstep or speedshift eep)
- Force maximum windows timer resolution (0.5ms), especially when using in-game fps cap.
- Manual interrupt affinity balancing for devices (+receive side scaling)
- NVMe timeout values (hidden in power plan by default)

Plenty more to add up the small percentages of benefit but that list could be endless. If you know other good tweaks it can easily add up.

Like I can at times achieve very close to G-sync smoothness with a 240/360 fps cap, but not even close out of the box.

actualthroway
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Re: G-sync only feels smooth when I have a twitch stream in the background. What gives?

Post by actualthroway » 22 Aug 2020, 10:57

MT_ wrote:
20 Aug 2020, 17:15
For smoothest possible gameplay a few key factors are indeed very important:

- Forced maximum clocks on CPU/GPU while in game. (Either through speedstep or speedshift eep)
- Force maximum windows timer resolution (0.5ms), especially when using in-game fps cap.
- Manual interrupt affinity balancing for devices (+receive side scaling)
- NVMe timeout values (hidden in power plan by default)

Plenty more to add up the small percentages of benefit but that list could be endless. If you know other good tweaks it can easily add up.

Like I can at times achieve very close to G-sync smoothness with a 240/360 fps cap, but not even close out of the box.
How do I achieve each of these listed factors?

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