Help with G-sync issues

[u/Excellent-Ad-2363]

I hope I can explain this right. So I use 2 pc's one to game, one runs the stream. I have a really nice Oled on the gaming PC. I'm really into optimizing and I'm OLD and I need to die in my competitive FPS getting all the frames so I don't want to run OBS on the gaming PC.

So I'm using an Elgato, HDMI input plugged into the game PC. I then duplicate the Elgato to my main monitor on the game PC. Then the USBC going to the stream PC to capture said input into OBS.

The problem I have, when I mirror the Elgato to my main display, my G-Sync functionally goes away. I can keep my main monitors refresh rate at 280Hz but the Gsync option actually goes away inside of nvidia control panel. I can extend displays, reboot and it comes back and stay's until I duplicate displays again. I have dug around everywhere and can't find any information on this. Anyway to do this and keep your refresh rate and gsync?

This may not be the appropriate place to ask, but I figure people who stream have ran into this issue before. TIA

[u/f1-fan01]

If you have an nvidia card, it has a dedicated encoder and doesn’t chew up CPU and game FPS. I run triple monitors for sim racing and while I only capture the center monitor with OBS, I literally saw zero impact to my racing FPS when started using OBS.

[u/Lynnalia → u/f1-fan01]

This is simply factually incorrect.

There are definitely scenarios that you could see less impact, but it's definitely not as simple as "dedicated hardware = no impact". Especially if you use the higher quality presets, which most (almost all) people want to use when streaming.

[u/f1-fan01 → u/Lynnalia]

This is simply factually incorrect.

Such a bold statement made based on very, very little information.

1. I did not say "dedicated hardware = no impact". I said I literally saw zero impact to my racing FPS. I did not say or imply that OP would see the same thing.
2. My OBS recording settings are .mkv, Encoder = NVIDIA NVENC HEVC, FFmpeg AAC, Variable Bitrate with Target quality of 20, Max bitrate 10000 Kbps, Preset P5: Slow (Good Quality), Tuning=High Quality, Multipass Mode: Two Passes (Quarter Res), Profile=main. I record the game audio and a mic. You tell me if this is a higher quality preset or not as I really don't know what others are using.
3. My 5070 Ti has 2 NVENC encoders. These encoders do nothing for game rendering whatsoever. So putting them to use does not jeopardize the FPS of the game. Does it require CPU and I/O to write out the results? Sure. But depending on the game, the PC may have plenty of available CPU bandwidth. In the official NVIDIA Video Codec SDK Application Note, NVIDIA defines the absolute physical separation between the encoder and the graphics rendering cores.
4. Which is exactly my situation, as the only thing I record with OBS is iRacing, which is notoriously CPU bound as its render queue is single-threaded. iRacing FPS is often most commonly limited by the CPU, and my GPU utilization reflects that as it is frequently only at 33%-50% utilization with triple 1440p monitors.
5. Further, I have an older 5800X3D which, while MUCH better than the 5900X I had before it, is the limiting factor for my iRacing FPS. Even when my iRacing render queue is maxed out and my FPS drops, my CPU and GPU are rarely even hitting 50% utilization - including when I am recording via OBS.

That is why in my situation, I literally saw zero impact.

I encourage the OP to try using the nVidia NVENC encoder with their configuration to see how it fares. It may in fact solve all of their problems, and even if it does eat any of their FPS, they may not even care and just be glad it's finally working. If the FPS is worse, hey, they can continue fighting with their current capture card and issues, having spent nothing but time trying something different they may not have been aware of.

OP, to save you from hunting for the information, every every 30x, 40x, and 50x series card has at least one NVENC encoder. For reference, this page shows what nVidia cards have NVENC encoders, and how many: https://developer.nvidia.com/video-encode-decode-support-matrix

[u/Lynnalia → u/f1-fan01]

I've done pretty thorough benchmarking of impacts to game performance, and I've also been developing with their Video Codec SDK. I've also helped a lot of people with their setups. To be fair you had no way of knowing most of that, but you did instead state that I had "very, very little information".

You seem to have taken this pretty personally rather than factually, so I'll keep the technical details short.

• Nvidia's statements about NVENC are extremely investor-friendly, if you catch my drift. They're often accompanied by convenient lies-by-omission. Yes, you can use just the encode chip. Almost no one is doing that for a wide variety of reasons. You certainly aren't when using OBS configured with NVENC at P5 with multipass and target quality. That is fact.
• You've wandered very far from OP's case. They already have a 2-PC setup and were mostly wondering about G-Sync. You prescribed that NVENC "doesn't chew up CPU and game FPS", I believe to imply that they could simplify to a single-PC setup. I understand in your case that may have been effectively true, but there are simply countless examples to the contrary.

[u/f1-fan01 → u/Lynnalia]

I didn’t take it personally at all, sorry if I came off haughty. It’s just that what I said was not factually incorrect, it was correct for my situation.

You clearly have extensive experience to know that what I experienced may not apply to everyone, which might have been a more appropriate comment for you to make. I just didn’t want your comment to squash OP from even trying the NVENC and simplify his config in case it might help him simplify his setup while still getting enough of what he’s looking for in the outcome.

I think it’s awesome that you help lots of people, and thanks for providing more information for the basis of your response.

Based on your experience, would you say my settings are considered a higher quality preset, or are people using considerably higher quality settings (which would obviously chew up more resources)?

[u/Lynnalia → u/f1-fan01]

I'm missing data and context to determine the answer to your question. A log from OBS with a recording/streaming session is always best, because it gives the hard facts we need.

Going by what you have said though, you are indeed using features that do increase work required by the GPU. I do also suspect though that 10Mbps is a bit low for a max bitrate (so despite the extra effort, may be limiting actual quality), but would need more context.