An apparatus and method for replacing a CPU cooling system, for example, a fan, while a computer continues to operate has a mechanism for maintenance personnel to signal that cooling fan replacement is about to begin. In response to the signal, a control mechanism causes the CPU to shift into an operating mode in which heat generation is reduced. In some cases, a clock frequency of the affected CPU and/or a duty cycle at which the CPU operates is reduced. After the fan has been replaced the control mechanism returns the CPU to a normal operational mode, for example, by increasing the clock frequency or duty cycle to a normal level. During the fan replacement procedure, the CPU and its software continues to run at lower than normal performance.