How does the processor react if there is nothing left to execute in the queue of tasks?

When there are no more tasks left in the CPU's task queue, the processor usually transitions to an idle state. In this state, it reduces activity to save energy and waits for new tasks to arrive. In modern systems, this may involve switching to low-power modes (e.g., C-States in x86 architecture). The processor does not execute any instructions related to user tasks until new work appears.