A volatile memory data save subsystem may include a coupling to a shared power source such as a chassis or rack battery, or generator. A data save trigger controller sends a data save command toward coupled volatile memory device(s) such as NVDIMMs and PCIe devices under specified conditions: a programmable amount of time passes without AC power, a voltage level drops below normal but is still sufficient to power the volatile memory device during a data save operation, the trigger controller is notified of an operating system shutdown command, or the trigger controller is notified of an explicit data save command without a system shutdown command. NVDIMMs can avoid reliance on dedicated supercapacitors and dedicated batteries. An NVDIMM may perform an asynchronous DRAM reset in response to the data save command. Voltage step downs may be coordinated among power supplies. After data is saved, power cycles and the system reboots.