trying to use all cpu cores or multiple gpus

[Paul]

I have 3 gpus and a 32c/64t cpu. I'm trying to render reflected light off metallic objects, and currently it's using 3 cores of cpu + 18% of one gpu, according to windows task manager.
I'm doing Path GPU + Sobol. Could you help me set up with better settings?

The scene is a few smooth metal objects reflecting light onto a flat concrete tile.

Thanks!

[B.Y.O.B.]

Make sure to switch the graph type in the task manager to "Cuda" when checking utilization of Nvidia GPUs (not sure what the equivalent for AMD GPUs would be).

About CPU usage, do you have the CPU device enabled in the "Devices" panel in the render properties?