A set associative cache memory , comprising: an M x N memory array of storage entries arranged as M sets by N ways, both M and N are integers greater than one; within each group of P mutually exclusive groups of the M sets, the N ways are separately powerable; and a controller that, for each group of the P groups, monitors a utilization trend of the group and dynamically causes power to be provided to a different number of ways of the N ways of the group during different time instances based on the utilization trend wherein the utilization trend of the group comprises a hit rate of the group, wherein the controller causes power to be provided to a larger number of ways of the N ways of the group when the hit rate of the group is below a first predetermined hit rate threshold and the number of ways of the group to which the controller is currently causing power to be provided is less than all the N ways of the group; and wherein the controller causes power to be provided to a smaller number of ways of the N ways of the group when the hit rate of the group is below a second predetermined hit rate threshold and the number of ways of the group to which the controller is currently causing power to be provided is all the N ways of the group; and wherein the second predetermined hit rate threshold is lower than the first predetermined hit rate threshold. an M x N memory array of storage entries arranged as M sets by N ways, both M and N are integers greater than one; within each group of P mutually exclusive groups of the M sets, the N ways are separately powerable; and a controller that, for each group of the P groups, monitors a utilization trend of the group and dynamically causes power to be provided to a different number of ways of the N ways of the group during different time instances based on the utilization trend wherein the utilization trend of the group comprises a hit rate of the group, wherein the controller causes power to be provided to a larger number of ways of the N ways of the group when the hit rate of the group is below a first predetermined hit rate threshold and the number of ways of the group to which the controller is currently causing power to be provided is less than all the N ways of the group; and wherein the controller causes power to be provided to a smaller number of ways of the N ways of the group when the hit rate of the group is below a second predetermined hit rate threshold and the number of ways of the group to which the controller is currently causing power to be provided is all the N ways of the group; and wherein the second predetermined hit rate threshold is lower than the first predetermined hit rate threshold. wherein the controller causes power to be provided to a larger number of ways of the N ways of the group when the hit rate of the group is below a first predetermined hit rate threshold and the number of ways of the group to which the controller is currently causing power to be provided is less than all the N ways of the group; and wherein the controller causes power to be provided to a smaller number of ways of the N ways of the group when the hit rate of the group is below a second predetermined hit rate threshold and the number of ways of the group to which the controller is currently causing power to be provided is all the N ways of the group; and wherein the second predetermined hit rate threshold is lower than the first predetermined hit rate threshold. <EOS>