Tested: Optix for GTX - The Good and the Bad

[moony]

@Todd_Takehana

Without RT cores, GTX cards do not benefit from any acceleration over CUDA when rendering with Optix

That’s not true - according my own testing at least.

If you are rendering using tiles (which is necessary for larger scenes or high resolutions on cards with lower GPU memory), Optix can give some very significant speed increases over CUDA, especially when coupled with adaptive sampling.

I did find that the benefits are scene specific though - so in some cases CUDA might be better, whereas in others Optix might give an advantage - depending on the number of tiles. I found that Optic was always comparable or faster than CUDA when rendering with between 12 and 48 tiles.

Cycles Development Updates

I have just graphed up the results above (along with a couple more to fill in the blanks). It appears that Optix rendering is far less impacted by reducing tile sizes than CUDA is when using adaptive sampling. The render times for Optix climb slowly and linearly as the tile size decreases, whereas using CUDA, there is a huge initial speed penalty for reducing the tile size. [image] When not using adaptive sampling, the data looks like this: [image] In conclusion - it appears that if you ca…