Current DDR3 SDRAMs have the capability of placing a rank in low-power mode. It may take as little as one DRAM cycle to place a DDR3 rank in low-power mode [2], however additional timing constraints must typically be met, depending on the DRAM command that is in progress. A rank in low-power mode must be powered back up before it can accept commands. Powering up a rank in DDR3 systems can take anywhere between 4-13 DRAM cycles [2]. Section 5.1 provides more details on the DDR3 DRAM interface that we model.