Does modeling use CPU or GPU? CPU cores?

I know you can render with CPU or GPU, latter being much faster, but what about modeling? Which is more heavily used? If I work with a model that has +4 million faces or just sculpt something is the main load on the CPU or the GPU?

What about cores then? Blender obviously supports multiple cores at least for rendering. Is there a noticeable difference in modeling if you have 4 cores rather than 6 or more?

I’m looking into buying a new computer soon and this information would really help me choose a processor. General suggestions are appreciated, but I must say that I will not get an Intel processor.

Modeling uses the CPU. In general the more cores the better but only if the software you are using is multithreaded for that task, in which I don’t think blender is in this regard. It usually starts to chug along around poly counts of 280k in edit mode. In object and sculpting modes the performance hit isn’t that bad.

How about 3ds Max or Maya?

There’s 2 aspects to this :

  • Transforming the model data. The action of moving the points, transforming them in space. Making new points, edges, faces and usnig various tools/Modifiers. This is done on CPU. How the CPU cores are used depends on the software making use of multithreading. For instance sculpting in blender is multithreaded.

  • Displaying the model data. The action of drawing the model data to the viewport so you can see it. This is generally done using OpenGL and is done on GPU. So while modeling speed will be affected by the CPU, viewport speed and responsiveness will be affected by the GPU.

According to Blender features, Blender keeps meshes in GPU memory for faster drawing. So i would look into getting a video card with a decent amount of VRAM. The term “modeling” is pretty vague, but you’ll need both a decent CPU and GPU. For simple box modeling you dont need a crazy CPU since you generally only transform a couple points at once. If you’re more into sculpting then a fast CPU will make a difference.

I currently have a PhenomII 955 quad core with 8Gb RAM and a Radeon 5850 1Gb graphics board. Blender is very responsive and i only start to get viewport lag around ~250k triangles in edit mode and maybe 750k-1mil in object mode or sculpting. However i’m not sure if thats due to my hardware or due to Blender’s viewport rendering code. Im thinking maybe the latter since I’ve run Softimage with higher polygon counts on slower machines with good responsiveness.

Thanks for your answer Muffy, you explained it very well. I got it now.