Although the JEDEC DDR5 standard is still under development, it looks that the new DDR5 DRAM will find its way to servers shipping this year.
According to Marc Greenberg, one of Cadence's experts on the memory market, close
participation in the JEDEC working groups offers an insight into how the standard will develop. Cadence, a controller and PHY vendor, can anticipate any potential changes on the way to final standardization. In the early days of the standardization, the company was able to adopt standard elements under development and work together with partners to get very early working silicon.
Cadence says it already has over a dozen design-ins. Greenberg expects to see a ramp of DDR5, driven by actual servers shipping with DDR5 inside. The value proposition, especially early on, is most attractive to enterprise, cloud, big data applications. In these initial shipments, 4800 will be the speed. DDR5 is offering a big leap in bit rate performance. It is expected to then hang at 4800 for 12-18 months, then go up to 5200, and 5600 after that.
Greenberg said that the DDR5 is more about density than speed. Using DDR5 it should be possible to have 512GB memory per channel for large dataset computing. When DDR4 was introduced, 16Gb die was impossible—now it is merely challenging. That is the entry capacity for DDR5, but it is expected to go to 24Gb and eventually 32Gb.
DDR5 is also quite well suited to stacking, so we can expect to see stacked devices allowing for even further capacity expansion. One is 3D. The other is LRDIMM technology, which allows for increased capacity.
With DDR5, you can expect to see 256GB DIMMs, with two slots per channel, so a 512GB machine. "In adition, many of these machines have 8 channels on a processor die, each die with 512GB, making a 4TB memory machine where you can access any byte in under 100ns. If a database index is 4TB, you can imagine how big a database could be supported," Greenberg said.
AMD’s EPYC ‘Genoa’ as well as Intel’s Xeon Scalable ‘Sapphire Rapids’ will support DDR5 DRAM when they launch sometome in the next couple of years.
Micron and SK Hynix have already announced sampling to partners of their DDR5 memory modules based on their 16 Gb chips. Samsung is also evaluating its 16 Gb DDR5 devices and modules.