Is the modeling (sculpting) in blender cpu depend? will it use compute core?

I know the modeling in blender is done on the cpu. What if the compute core is enabled? Will it then use the graphics card for modeling? I know when rendering a scene it depends on which one is enabled, cpu or gpu. I am asking this question, so I can find out if it’s more important to have powerful cpu and ram, versus bigger gpu, when sculpting.

In sculpt mode, the GPU is used solely for displaying your work. It will play a bigger role in 2.8 when you are using Eevee to display your model.
For now, sculpting is a CPU and especially RAM heavy task. With a growing vertex count, your machine will get really busy really soon.

I think this means, that besides having a good enough graphics card for display, that it’s more important to have processing power, and enough ram to work in. Unless of course, I was doing renderings.

Somewhat, yes.
But then processing power != processing power.
It is a tricky thing. There is a lot to consider and evaluate to find a sweet spot between single core clock speed, clock count, RAM size and bandwith… Our computers and the software we use are very complex and delicate things.