An architectural level technique for a high performance and lowenergy cache memory is proposed in this paper.The key idea of our approach is to divide a cache memory into several number of cache blocks and to activate a fewparts of the cache blocks.The threshold voltage of each cache block is dynamically changed according to an utilization of each block.Frequently accessed cache blocks are woken up and others are put to sleep by controlling the threshold voltage.Since time overhead to change the threshold voltage can not be neglected,predicting a cache block which will be accessed in next cycle is important. History based prediction technique to predict cache blocks which should be woken up is also proposed.Experimental results demonstrated that the leakage energy dissipation in cache memories optimized by our approach can be less than 5%of energy dissipation in a cache memory which does not employ our approach.