I am new to 2.8 and i’m not sure if i have setting that needs to be changed, but when i am rendering in blender 2.8 eevee, and i am watching my mac activity monitor, i can see my computer is running at maybe half effort. and blender is running slow. why does blender not use ally my CPU’s?
blender use mainly the graphic card to render,
What you see in CPU usage should be mainly mesh evaluation / scene preparation , all that kind of stuff.
it’s your GPU that do the heavy work, and using CPU with eevee wouldn’t be relevant, given it use mainly real time techniques tailored for GPUs.
I’m having the same issue. My scene has smoke and fire physics on a mesh with 31k verts. I have an I7 8700k overclocked and gtx 1080. Took over an hour to play the scene in the timeline. I’m following a tutorial online so I assume the scene setup isnt to over the top. But my GPU barely assisted any of it. 99 percent cpu the entire time
It’s totally the opposite issue, in your case it’s the CPU that is doing the heavy work of running the simulation, previewing it in the viewport on the GPU is easy compared to that , so the GPU is waiting for the CPU computations.
CPU and GPU don’t do the same things and sometime one is waiting for the other to complete.
In some case you can have CPU+GPU working on the same things like in a cycles render, but for most of the different calculations it’s not.