A method, and a corresponding system, for managing under-utilized resources in a computer system includes the steps of monitoring performance of workloads executing on the computer system, where the workloads consume resources, determining resource demand and utilization by the workloads, comparing the workload performance to user-defined performance targets and resource utilization by the workloads to user-defined utilization targets, using the comparison results, determining if one or more resources may be assigned to a free resource pool, and assigning the determined resources to the free resource pool.