Iray doesn't use GPU

Dave McH

Hello!

I noticed some strange behavior while rendering "heavy" scenes.

If render utilises all VRAM and starts to use RAM, GPU load drops to zero and all render goes on CPU.

This realy bores me because, I thougt I could add second GPU for even faster render but now I see no poing in that.

Even more, some scenes takes 16+ GB so even 1080ti won't do the job.

I may be mistaken but as I heard in dual GPU configuration only primary card VRAM is used.

The question is simple as it only can be, how to make all CUDA cores work as they suppose to, even though VRAM is full?

Richard Haseltine

Each GPU has to load its own copy of the scene, if it can't hold the scene it drops out. If you have multiple GPUs then any that can load the scene will be used, any that can't will not.

fastbike1

@Dave McH  "The question is simple as it only can be, how to make all CUDA cores work as they suppose to, even though VRAM is full?"

An artist needs to build a scene that can fit in the available VRAM. There are several products that can help reduce the amount of Vram needed, but it still comes down to the artist. This is no different in concept than trying to put additional files on a hard drive that is full.

This is not new information.

Dave McH

I see, well I'm not a computer guy, so I though it can use RAM only.

I know about the script for scaling down textures and etc. But there is somthing I'd like to know.

If I have a huge scene, for instance a building but render only one small part, like a room, do I have to remove everything what is out of field of view.

I mean other flats, cars outside. I don't know woh it works exactly whether it loads everything or just visible area.

Daywalker Designs

Dave McH said:

I see, well I'm not a computer guy, so I though it can use RAM only.

I know about the script for scaling down textures and etc. But there is somthing I'd like to know.

If I have a huge scene, for instance a building but render only one small part, like a room, do I have to remove everything what is out of field of view.

I mean other flats, cars outside. I don't know woh it works exactly whether it loads everything or just visible area.

Anything outside the viewport, unless it's critical for shadows in a scene, can be removed from the scene to reduce how much VRAM would be used. The script mentioned can be used to reduce the size of texture maps as well.