Question / Help FPS drop when opening OBS or using Discord Go-Live

[Vinilla]

To basically put it, when playing a game, my fps is stable, and very high. The moment I open or use either of these applications, my framerate still stays high, while being cut in half visually. e.g. 144+ fps feels like half of what it reports as.

System Specs:
MOBO - Asus Prime Deluxe X299
CPU - i9 7920x @ 4.3GHz (Encoding Stability Focused Overclock)
RAM - 64GB 3600MHz C16 DDR4
GPU - 2x EVGA 1080ti FTW3 Elites in SLI
Storage - 512GB Samsung 960 Pro Boot Drive, identical Game Drive, and a few more SSDs/HDDs
PSU - 2x AX1200i 1200W PSUs in a Redundancy setup

Monitors:
Main/Center - Brand New Asus XG279Q == 144hz 1ms GSync IPS Gaming Monitor running at 170hz
Sides - 2x Asus 4k 60hz productivity displays
All using Displayport 1.2 cables.

NVIDIA Settings:
Monitor Tech: GSync Compatible
Power Mode: Prefer Max Performance
Preferred Refresh Rate: Highest Available
SLI Mode: NVIDIA Default (Destiny 2 doesn't support SLI, so it is set to Single GPU mode)
Shader Cache: ON
Texture Filtering LOD - Clamp
Texture Filtering Quality - High Quality
NO VSYNC ANYWHERE

OBS Setup:
Plugins Installed == OBS NDI, OBS.Live, Twitchy

Video Tab:
Canvas Size: 2560x1440
Output Size: 1920x1080 (Also tested 1280x720)
Sharpening Filter: Lanczos (Tried all of them)
FPS: Integer Value of 60fps

Stream/Encoder Settings:
Stream Server- US West: Los Angeles, CA
Rescale Output - Unchecked
Rate Control - CBR
Bitrate - 6500 kbps
Custom Buffer Size - Unchecked
Keyframe Interval - 0
CPU Preset - Ultrafast (tried settings from medium to ultrafast, stream can handle fast preset)
Profile - High (tried Main as well)
Tune - None
x264 Options - None



So to start, this PC was initially built to handle Gaming/Streaming on one system. It can handle it, just can't handle the FPS bug with it. So I have a separate PC using OBS NDI to relay the connection to it, to let it handle the streaming/encoding, while this one stays untouched. But guess what? FPS bug still persists.

To isolate the issue, I ran Destiny 2 as the test game (issue also existed with other games such as Modern Warfare, and even Team Fortress 2) and began my rundown of tests. Now before you link me to all the OBS Guides and Tweaks and fixes etc, I'VE TRIED THEM ALL. From encoding settings, to core affinity, to process prioritization, GPU Overload/Utilization, frame capping games so it can share the GPU resources with OBS. Yes, nothing worked. If only I can make a local video showing the FPS lag, but that's not possible. And to be very clear, THE TEST STREAM IS SMOOTH, FPS CLIENT-SIDE IS UNSTABLE.

I've uploaded a log to the OBS Discord under the same support channel, and had users linking me the same resources I've already tested/debugged. So I decided to make this forum post to seek additional help in hopes of finding a solution to my issue, and also logging it under everything I test or try so we can nail down the culprit.

Log File: https://obsproject.com/logs/Kw_RpDbGCqRmXmdk
(Fixed the Color Range, and IP Binding is simply because I had to force my 10gbe adapter to use OBS)

Attempted Fixes will go under here as I try/respond to suggestions.
===================================================

 

[koala]

OBS's game capture doesn't work good with SLI setups. It's possible that framerate cutting in half may result by this.
It's not a rendering or encoding issue with OBS, because in your log there are no lagged or lost frames due to rendering or encoding lag.

This is a lengthy and comprehensive thread that discusses OBS with SLI:

Question / Help - The ongoing saga with SLI

Two 970gtx's and Intel i7-8700 cpu and no matter what setting I try, SMITE Game Capture always stutters. SLI/Crossfire capture mode makes no difference. Limiting the game's frame rate, no difference. Changing OBS's settings in the nVidia panel, no difference. Running the game fullscreen or...

obsproject.com

 

[Vinilla]

SLI is disabled for OBS, and the game in question does not allow third-party code injection for game capture (Destiny 2). Using Monitor Capture, and I don't need to have a game running for it to get sluggish on my end. I am led to believe it is an issue with OBS being unstable on lower refresh-rate monitors while your primary monitor is a higher refresh-rate.

And I am not about to buy 3 identical monitors, given all those guides/troubleshooting tips say "run your monitor at 60fps." I didn't buy a high refresh-rate monitor to play at low refresh-rates.

 

[FerretBomb]

This is a problem with Windows, not OBS. Windows does not deal with disparate refresh rates well, with hardware accelerated applications. A patch is supposedly coming in Win10 2004, expected sometime later this year.

Until then, as much as you may not like it, the fix is to run all your monitors at the same refresh rate.
You can also disable the Preview window in OBS, which can help in some cases.

For Destiny 2, it's also advised to run the game in Fullscreen Windowed mode, and use a Window Capture, not a Display Capture. DC is the least-performant capture method, and should be avoided if at all possible.
Also, if you are not using vsync, it's recommended to run OBS as Administrator. A workaround in 24.0.3 was added that allows OBS to take GPU priority over un-locked games, ensuring that all its housekeeping tasks get done before the game grabs the rest of the GPU time.