They are called NVDIMMs. One example http://www.vikingtechnology.com/arxcis-nv http://www.vikingtechnology.com/arxcis-nv I think some of them are protected by

They are called NVDIMMs. One example http://www.vikingtechnology.com/arxcis-nv http://www.vikingtechnology.com/arxcis-nv I think some of them are protected by both a battery and flash memory for long term backup.