I’m not 100% clear about what your asking but I think you might be confusing OpenMP with MPI programming. NCPUS is used with OpenMP to set the number of threads that are spawned on a stand-alone symetric multi-processor (SMP) system. OpenMP does not enable you to spawn threads on other nodes of your cluster. To run parallel executables across multiple cluster nodes, you’ll need to use MPI instead.
Note that on some Linux distributions there are utilities, taskset and numactl, which do allow you to bind threads to a particular processor on a SMP system. MPI does not have this capabilbity.