CYCLES X not utilizing GPU if CPU is also enabled for rendering

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1

Before raising a bug report I want to make sure this is not by design and maybe there is just another step to deal with.

I am using Blender 3.0 stable, RTX 3090, Dec 22 studio drivers 472.84. Intel 7700k

Basically, long story short, if I use GPU rendering, so in preferences set to CUDA or OPTIX, if I have both the GPU and CPU enabled then when rendering on GPU compute I will see my GPU usage go up for just a short half second blip and then goes back down to 0-1% and only renders on the CPU. If I uncheck the CPU in CUDA or OPTIX then GPU usage remains at 100% and I render just shy of 30 times faster, but I would still like my CPU to work if at all possible.

Before I go around reporting this as a bug, I am wondering if anyone else has had this issue, and if there is any special steps required to make this work that are perhaps by design.

2

Do not happen to me in Optix in 5800H+RTX3060, but GPU+CPU is slower than just GPU. Same drivers as you.

3

Interesting. Well it’s certainly working as is. Once I know how to make both work I will do a side by side test. It is weird because in some scenes both work and in others they don’t. Been a blender user for close to 14 years now, maybe longer, so I have covered all the obvious things it could be, but besides the obvious, I know a few things have changed in 3.0 so I am not sure if anything that has changed could be whats causing this and I am just inadvertently checking on a feature that is currently CPU only or something like that…