Question Global Apps/Games Stutter while mutlitasking


Sep 2, 2015

So I have recently built myself a brand new shiny computer. A brand new i7-10700K, 16GB of 3600MHz RAM and a placeholder (yet still very powerful) GTX 1660S. Just to make things even better for myself, the CPU is OC'd at a respectable 5.0GHz at all times and the GPU has a 100Mhz OC on both core and memory clock. The RAM is running at 3600MHz with XMP enabled.

The performance is great when it comes to single tasks, but as I want to be streaming, I need to run OBS while playing.
I've noticed, testing OBS performance today, that my PC has very bad stuttering when doing random things, which is clearly not hardware limitation, as my CPU doesn't go over 25%-30%, and it's the same situation for my GPU. Running a stream, youtube video, video media, OBS stream preview and other various things will affect my performance hugely, while NOT changing the in-game FPS counter. (Regardless of the video quality or resolution/browser usage) A 160p15 stream will stutter my PC just as much as a 1080p60 one.

For example, running League of Legends at 400FPS on my 144Hz monitor is butter smooth, but as soon as I have OBS on my second monitor looking at my stream preview, it starts stuttering badly, looking like 60FPS, while still displaying 400FPS in game. My hardware isn't struggling whatsoever.

The video player will have insane stutter while stream preview is running (but only while I'm moving my mouse on the video player, which will make the time bar pop up), to the point where it looks like a slideshow. When I stop moving my mouse and the time bar goes away, the lag goes away along with it. It also stops when I close all other windows/media from playing, but will have stutter during the appearance/disapearance of the time bar. But if another video/stream is running, it will stay. It also happens on a smaller scale, where if I try to quickly move a window (task manager for example) it will be butter smooth until a video/stream/preview is running. It will then look more like 60FPS instead of 144. It doesn't only happen with OBS or videos, anything similar causes the issue and it makes gaming very unenjoyable while watching youtube/stream or even just streaming myself. My second monitor becomes pretty much useless.

My main monitor is a 144Hz display plugged into Displayport, while my second is also a 144Hz monitor, but currently capped at 60Hz due to its HDMI connection.

I have tried running only my main monitor and the issue seems to have gone away, even when running a 1080p60 stream, a 4k60 youtube video and a 1080p60 video file all at once. Is it possible that the limited HDMI bandwitdth is applying to both monitors? I will be getting a second displayport regardless. Should I get a specific version of DP?

I can do more tests if anything else could help troubleshoot, perhaps it's something caused by the "extend display" setting?

Thanks for the help!

P.S. I tested and realized that if all videos are running on the same display, no issue at all is happening, but as soon as one video is on the second monitor, stuttering happens. I'm fairly certain, at this point, that the HDMI cable is at fault, but I will post this regardless hoping for confirmation and maybe an explanation for it, as I am interested to learn.

EDIT: Perhaps this thread should be in the displays section? I thought it was software, but is seems more focused towards cable bandwidth and such at this point.