OBS encoding overloaded, despite low CPU / GPU utilization?

I would like to stream ARK on Twitch, but this is not possible with more than 10-25 fps.

Short to my PC

Operating system: Win10 Pro

CPU: Intel i9 9900k

RAM: 32GB

GPU: RTX 2080ti

Internet: Download 150 Mbit / s

Upload 10 Mbps

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If I play ARK without streaming it runs without problems on the highest possible settings in 2560x1440 and 144hz.

Now if I turn on OBS and want to stream it to 720p I have 10-25fps in the stream. The game itself runs smoothly and both CPU and GPU utilization are around 30-50% while the game and the stream are running.
The kb / s at OBS are quite constant at 6000, where I've tried everything here from 2000 to just 6000 (maximum what Twitch assumes).

I do not know what to do anymore to solve the problem.

OBS shows "Encoding overloaded" during the stream

What I do not understand is how can this be overloaded if the whole system is not overloaded.

I also played with the graphics settings in Ark ansich of medium -> high -> Episch no difference to the FPS in OBS can be seen.

Alone, if I set everything to low, the stream suddenly runs at 60FPS.

But since other streamer with much worse systems can stream the game to medium to high settings because what is wrong.

Are you streaming with the CPU? Try the following settings.

1080p @ 60fps

6000bitrate

preset medium

Did not help unfortunately = /

Then I can't imagine why that is so, I'm sorry.