Use a Second GPU to Boost OBS Performance

[DarkSwordsman]

So I was having issues with OBS dropping so many rendered frames when playing PUBG. I was recording at 720p60 @ 6000 Kbps, veryfast. I had remembered about an hour ago, it was dropping on a different game when it was on a monitor going through Integrated Graphics, but when I moved OBS over to a different monitor using my GTX 970, it was perfect with no issues.

 

So I then thought I should take the 650 Ti from my streaming PC (which I am trying not to use since single-PC streaming, long-story short, is easier). 

 

I plopped it in and tested with PUBG.

 

Now I know I don't have a lot of results since I'm about to go to bed, but I at least wanted to share my findings.

 

All testing is done at 720p60 @ 6000 Kbps, veryfast, with a tip jar, webcam, and desktop capture.

 

GTX 970 only: averaged about 50-55 FPS, dropped about 8-10% of frames. 

GTX 970 with OBS on GTX 650 Ti screen: averaged 60 FPS with some outlier 55-59 FPS shots, and dropped only about 3-4% of frames.

Now I know I am still dropping frames, but that's a significant decrease. 

 

I am now wondering if there are any settings I can do in OBS to push it farther since it seems that the GTX 970 still does some rendering, and actually may need some processing power to account for the separately rendered screen.

What I mean by accounting for the separate screen: Note the following image:

 

 

This hump is me moving OBS to the 650 Ti monitor and back while not recording. It went from (970 and 650 Ti respectively) 6%, 0% to 11%, 32% to 6%, 0%. So it seems that the GTX 970 is doing extra processing to account for the extra screen, but isn't caught up rendering the scene on OBS.

 

Just thought I'd share. I will be testing this further, especially if I can bump it down to 48, or even 30 FPS if needed, though I would not like to.

[GER_T4IGA]

I don't have any experience with dual GPU streaming but battle(non)sense made a great video about different recording software, comparing thei performance impact also using a second GPU. You might want to have a look at it. It is really informative and could help your case.
 

 

If I recall correctly what he said, your 650 Ti might be to slow to help much. He used a 1080+1050-setup without any issues.

[WereCat]

21 minutes ago, DarkSwordsman said:

 

 

All testing is done at 720p60 @ 6000 Kbps, veryfast, with a tip jar, webcam, and desktop capture.

 

 

This implies you are using your CPU to encode instead of GPU.

You cant choose a "Very Fast" Encoding Preset when using NVENC to encode, only if you are using x264.

 

Can you screenshot your OBS settings?

[DarkSwordsman]

6 hours ago, GER_T4IGA said:

I don't have any experience with dual GPU streaming but battle(non)sense made a great video about different recording software, comparing thei performance impact also using a second GPU. You might want to have a look at it. It is really informative and could help your case.

 

If I recall correctly what he said, your 650 Ti might be to slow to help much. He used a 1080+1050-setup without any issues.

I'll take a look when I get home. And I figured the 650 Ti might not be the best, but it's what I have. Got it for $60 on eBay.

6 hours ago, WereCat said:

This implies you are using your CPU to encode instead of GPU.

You cant choose a "Very Fast" Encoding Preset when using NVENC to encode, only if you are using x264.

 

Can you screenshot your OBS settings?

I'll take a screenshot when I get home. And yes, I am using the CPU to encode. It's an i7-2600k @ 4.5Ghz. It was sitting at about 75% utilization in task manager while playing, and there were literally no dropped frames from encoding lag.

 

I did try using NVENC with both GPUs and it tanked very hard. 

[WereCat]

1 hour ago, DarkSwordsman said:

I'll take a look when I get home. And I figured the 650 Ti might not be the best, but it's what I have. Got it for $60 on eBay.

I'll take a screenshot when I get home. And yes, I am using the CPU to encode. It's an i7-2600k @ 4.5Ghz. It was sitting at about 75% utilization in task manager while playing, and there were literally no dropped frames from encoding lag.

 

I did try using NVENC with both GPUs and it tanked very hard. 

Well then there is very little to gain if you are using CPU to encode.

NVENC should give you the best performance if you are using 2 GPUs, you just must not forget to tell OBS which one to use so that its not using the one you are playing on.

[DarkSwordsman]

On 9/18/2018 at 1:22 PM, WereCat said:

Well then there is very little to gain if you are using CPU to encode.

NVENC should give you the best performance if you are using 2 GPUs, you just must not forget to tell OBS which one to use so that its not using the one you are playing on.

I did tell OBS to use each one. The issue is that it's a completely separate part of the card that encodes and decodes video. In most cases, NVENC works well, but only for very low quality streams (i.e: 720p30 @2500-3000 Kbps).

 

I really think there is quite a bit to gain if I'm using the CPU to encode. In my testing with various games, there were little to no (0% average with 0.5% outliers) dropped encoding frames, even up to 720p60 and 1080p30 @ 6000 Kbps. The real issue, which was mostly apparently in PUBG, was dropped rendering frames (which means dropped frames due to the graphics card taking too long to render the scene). 

 

As I said, running OBS on the 650 Ti-powered screen was just enough to get that rendering lag down under 10 frames total for about 20 minutes of gameplay.