8-fold stacked chips at a lower height than previous 4-fold stacks for DDR4 memory chips enable previously unattainable capacities for DDR5 RAM for the future, as Samsung is showing at the Hot Chips 33 conference . 512 GB could become so quickly and, above all, affordable – something that was not possible with DDR4.
4 TB RAM has theoretically been supporting some processors and platforms for years, starting with thus AMD has with the Epyc processors in the x86 server world. But in the last few years there was still a world of difference between theory and practice, the most common memory modules are still 32 or 64 GB in size, even 128 GB memory bars were and are rare. In the area of even larger capacities, it becomes exotic or simply does not exist. The 4 TByte could not be reached in this way.
Samsung DDR5 – goals and bonuses compared to DDR4
At the opening of the Hot Chips 33, Samsung shows efforts for higher capacities, which are to become visible for the first time with DDR5. The packaging is once again attracting a great deal of attention, because there is still potential for optimization here. If four dies were recently stacked in a classic, high-capacity DDR4 memory chip, there will be eight dies in the future. Thinner wafers, significantly reduced gaps, adapted TSVs and the constant consideration of the issue of cooling ultimately enable an overall package that is only 1 mm in height despite eight chips – with DDR4 it was 1.2 mm with four dies.
Samsung DDR5 chip with eight stacked die
TByte era for servers should begin in 2022
The overall package should still work extremely efficiently. The voltage of 1.1 volts specified as part of the DDR5 specifications already partially ensures that the adapted manufacturing process and the voltage regulation directly on the module should ensure an almost equally large percentage gain. From the end of this year, Samsung wants to manufacture the 512 GByte modules in large series, so that they are ready for the start of the server processors in the coming year – then the TByte era for servers could begin. The company does not expect the crossover from DDR4 to DDR5 in the mainstream before the year 2023/2024.
Samsung DDR5 chip with eight stacked die 
Samsung DDR5 – goals and bonuses over DDR4