Different parts of NX utilize different numbers of CPU cores. Generally speaking, NX itself, for many of it's modeling and display tasks, can utilize up to four cores. Recently some of the rendering code has been enhanced to support even more than that and can even be distributed across a wide network of CPU's and GPU's. And as for the simulation solvers, such as NASTRAN, they can be set-up to utilize a large number of CPU's/cores simultaneously to solve complex problems.