OBS maxes out CPU since GPU upgrade

Djigr

New Member
Hi,

I regularly stream from my laptop since a year (Acer ConceptD 7 Ezel, NVIDIA RTX A3000, i7-11800H) with OBS, with very correct results, never had any trouble streaming any game at 1080p and 30fps.
I recently got an AMD Radeon RX 7900 XT and installed it as an eGPU with a Razer Core X Chroma. Installation went fine, games are using the eGPU without any problem and performance was higher, so the GPU is functional on that part.
However, when I simply start OBS, the CPU reaches 100% use, and everything becomes laggy. I almost can’t stream anymore, while it was doing fine before.
I couldn’t find any help elsewhere, as everybody recommends lowering specs, but I didn’t get a better GPU to stream at a worse quality, this is nonsense.
Why is the CPU even impacted? Is it something relating to AMD’s encoder?
As always, here is the log: https://obsproject.com/logs/0hdZNZcYkOZ8TLdC
 

Djigr

New Member
Thank you, I had already checked the analyzer, but it doesn’t make any sense: I have not changed any parameter in OBS since adding an eGPU, there is no reason to believe my new GPU would be more overloaded than my old GPU, as the new one is generally more powerful than the older one.
Unless AMD’s encoder is that worse than NVIDIA’s that it sets it back years and years behind, and an A3000 ends up better than last month’s AMD cards, but it seems unlikely.
Also, if the GPU was overloaded, why is it using only 20% of it?
 

rockbottom

Active Member
Configuration, TB not working properly or something else going on. Don't believe it's OBS.

Have you tried gaming on the 7900XT & off-loading the encoding to either the A3000 or your iGPU?

The A3000 will encode better than the AMD, heck your iGPU more than likely will too.
 

rockbottom

Active Member

Windows 10 & Windows 11 Compatible Graphics Chipsets
Compatible AMD graphics chipsets:
  • Radeon ™ RX 6600XT
  • Radeon ™ RX 6700XT
  • Radeon ™ RX 6800XT
  • Radeon ™ RX 6900XT
  • Radeon ™ RX 5000 Series
  • Radeon ™ RX Vega Series
  • Radeon ™ RX 500 Series
  • Radeon ™ R9 Series
  • Radeon ™ Pro Series
Please verify graphics card is under max dimensions above.
 

Djigr

New Member
Configuration, TB not working properly or something else going on. Don't believe it's OBS.

Have you tried gaming on the 7900XT & off-loading the encoding to either the A3000 or your iGPU?

The A3000 will encode better than the AMD, heck your iGPU more than likely will too.
I have tried choosing the NVENC encoder and even x264, but OBS didn’t care at all. Honestly, there seems to be a weird communication between the different cards that, in the end, overload the CPU.

I have managed to force OBS to only consider the A3000 by hotplugging the Core X (aka starting the laptop with the Core X’s thunderbolt unplugged, starting OBS, then plugging the Core X), and managed to run a game in parallel on the 7900 XT. Disgusting, but efficient. Not sure that’s a very good thing to do, hotplugging usually makes things unstable.

CPU runs normally, encoding with the A3000 as I did before, and I can still benefit from the performance boost of the 7900 XT for games.

I am surprised by what you said about AMD encoding worse than iGPUs and the A3000. I had heard that AMD had made a lot of improvement in encoding, and that both green and red team could compete now on that ground.


Windows 10 & Windows 11 Compatible Graphics Chipsets
Compatible AMD graphics chipsets:
  • Radeon ™ RX 6600XT
  • Radeon ™ RX 6700XT
  • Radeon ™ RX 6800XT
  • Radeon ™ RX 6900XT
  • Radeon ™ RX 5000 Series
  • Radeon ™ RX Vega Series
  • Radeon ™ RX 500 Series
  • Radeon ™ R9 Series
  • Radeon ™ Pro Series
Please verify graphics card is under max dimensions above.
I expect Razer has not yet updated their compatibility list, because I have not had any other problem with this card (that is very new, came out in December). Games and analyses run fine, only needed a BIOS update to make it work.
 

rockbottom

Active Member
Not what from what I've seen & when it comes to creation it's not even close.

That list will get updated when the driver is released.
 

Djigr

New Member
Hi,

So after a few weeks of turning this problem upside-down, I have found a solution to force OBS to use the internal GPU instead of the external GPU.
The cause of the problem, I think, would be that the eGPU is bottlenecked by the Thunderbolt3 interface. Doing both the encoding and gaming on the eGPU forces back-and-forth in the TB3, which slows everything down.
It is, IMO, more probable than having an 7900 XT being incapable of even running OBS.
In order to circumvent the problem, the trick is to use Windows’ settings.
In Windows 11, go to "Display", then "Graphics", then either OBS is already in the list, or you find the exe with "Add an app", then click on OBS in the list and "Options", then in "Specific GPU" you can specify your internal GPU.
In my case, I chose the RTX A3000, and OBS runs just fine now.

1674836724001.png


Good day everyone!
 

Harold

Active Member
Thunderbolt connected egpus do not have the link performance required to use OBS with them in any way.
Thunderbolt 3 is limited to pci-e 3.0 x4
OBS requires closer to x6 on its own to function properly.
 

pablofuente

New Member
Hello @Harold, thanks so much for clarifying this. I have an eGPU connected to my iMac Pro (WX9100), but the other day, my OBS froze and crashed during a live stream. I believe OBS is not taking advantage of it at all, and it might actually have caused it...please look at this report. My question for you is, would I be better off if I disconnecting it? I have an iMac Pro with a Radeon Vega 64 (16 GB HBM2 RAM)/ the Mac has 64 GB DDR4. If yes, how do you suggest I connect the 4 monitors I use? My issue is not enough thunderbolt ports...thanks again!
1706018626990.png
 
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