Gpu rendering with 2 gpus

[Hemikidd]

I was researching this and i looked at some forums on this website and i was wondering if I can set the rendering task to one gpu and play games or do something else like watch a video with the other gpu. Is that possible?

[Kisai]

1 hour ago, Hemikidd said:

I was researching this and i looked at some forums on this website and i was wondering if I can set the rendering task to one gpu and play games or do something else like watch a video with the other gpu. Is that possible?

Yes in theory. In practice it's not doing what you think it's doing.

 

Certain things, like games, can be told to only use the dedicated GPU, regardless of which GPU the actual display is connected to. So you can for example plug a 4K monitor into the Displayport of a nVidia card, and then plug a HDMI into the iGPU on the motherboard, and you can drag that game between the two monitors with little or no loss in frame rate.

 

With that said, that's not free either. The ideal situation you would be doing this is on a laptop that is connected to a USB-C docking station. Displaylink (not displayport) docks will neuter your GPU if you use them, which is why you can only use the Displaylink docks as secondary monitors. However, you can drag a window running on the dedicated GPU to the software GPU of the displaylink dock and it will still work as though it's on the hardware one. 

 

I don't recommend it unless you have a specific use case in mind, because most CAD/Modeling software just immediately gloms on to all available GPU's, and games are really the exception where the games are only designed to be run off the primary GPU, even if there are multiple in the system. Not all CAD software is smart though, AutoCAD will only use the GPU connected to the primary monitor*.

 

* It will correctly grab an nVidia GPU on the primary monitor if going through the Intel iGPU on a laptop, but not on a desktop, where monitors plugged into the iGPU end up being used first, even if there are monitors plugged into the nVidia GPU.

 

This is where fiddling with the task manager comes in. You can actually "force" Windows to direct GPU requests to specific devices, so say you had OBS recording a game, you might direct your game to use one dedicated GPU but direct OBS not to use the same one if you're using software encoding. If you have TWO GPU's however you can direct OBS to use the other GPU for encoding. This is still not memory efficient though and a lot of video capture stuff is really a sort of voodoo as to what produces the least laggy output and which produces the best quality output.

 

Also keep in mind that what windows is doing is directing the rendering and compositing, it's not directing the underlying ffmpeg.

[PositiveRaisin2]

i think that would work

[Lord Mirdalan]

5 hours ago, Hemikidd said:

-snip-

Sure. For example: Dedicate GPU1 to the render, and GPU0 will run the game by default (in most cases).

 

But YMMV

[Loote]

To make sure your resources are handled the way you want you could try to imitate stuff from x gamers 1 pc videos. You're going to loose some performance, but it should be perfectly playable, that is, I assume you've got 2 DGPUs, using IGPU while also rendering might lead to severe memory bottleneck(if rendering is RAM heavy).

[Hemikidd]

thanks