The slides reveal ultra-low voltage DDR4-2400 has already been successfully tested at a voltage of just 1.0V, and it seems standard DDR4 will not require more than 1.2V. Compared to 1.5V DDR3-2133, the 30nm class 2Gb DDR4 prototype chips achieve 40 percent power savings in load and a 35 percent standby power reduction.
You can check out more DDR4 slides at ComputerBase. DDR5 was also discussed, here's a short list of potential features of the DDR5 specification:
Stacking technology: 3D stacking + TSV New memory architecture: revolutionary vs evolutionary High speed interface with socketless approach Highly integrated packaging Hybrid memory cube: memory + interface logic Continue to grow speed and density