JEDEC specifies that the pull-up resistor for the SAVE_N pin on NVDIMMs belongs on the motherboard. Micron designs NVDIMM with and without the pull-up resistor to support all customers, since some current motherboards do not include the SAVE_N pull-up resistor.
NVDIMMs need power to back up DRAM content to the onboard NAND when system power is absent. Backup power can be supplied either through the motherboard or by a tethered backup power supply. Micron PowerGEMs are a tethered backup power supply. PowerGEMs are supercapacitor-based power modules intended for use with one or more of Micron's NVDIMMs. The PowerGEMs utilize either supercapacitors or hybrid supercapacitors, which enable designs for PCIe and 2.5-inch drive bay small form factors.