Example implementations relate to coupling volatile memory devices to a power source. In example implementations, data may be copied from a first volatile memory device on a memory module to non-volatile memory. The first volatile memory device may cease to be powered after data is copied from the first volatile memory device to non-volatile memory. After the first volatile memory device has ceased to be powered, data may be copied from a second volatile memory device on the memory module to non-volatile memory. The second volatile memory device may cease to be powered after data is copied from the second volatile memory device to non-volatile memory.