Last week, JEDEC announced that the upcoming DDR5 memory standard will offer double the bandwidth and density of DDR4, improve channel efficiency, and offer better power efficiency as well. The new standard isn’t expected to be in-market until 2020 — JEDEC will finalize the standard next year, and announce new details at its Server Forum event in Santa Clara.
A new DDR5 memory standard for servers, desktops, and laptops would offer improved bandwidth (at least eventually), though memory latency still always jumps between generations and rarely much surpasses the original standard, even at high frequency. Higher bandwidth is always helpful in server workloads and some workstation applications, and desktops and laptops with integrated graphics always benefit from having more memory bandwidth to use for gaming or 3D applications.
JEDEC also announced that its NVDIMM-P specification standard is also moving along well. We’ve talked several times in the past about the hardware efforts to move NAND — flash memory — into DIMM sockets and data centers. Intel’s 3D XPoint memory, Optane, is also designed to fit in DIMM sockets, though the company hasn’t launched that version yet.
NVDIMM-P is a new NVDIMM standard and will take its place among the multiple variants already in-market. NVDIMM-N matches an equal amount of DRAM and NAND flash on the same DIMM. NVDIMM-F uses a small amount of DRAM to buffer a large amount of flash and is typically used as an alternative to a PCI Express SSD. These drives have lower latency and better responsiveness when placed on the DRAM bus instead of the PCIe interface. NVDIMM-P combines NAND and DRAM on a single chip and can interface with two different access mechanisms while using the existing DDR4 standard.
Back when DDR4 was new, we discussed some of the future technologies that might replace DRAM in a number of devices, including Hybrid Memory Cube, High Bandwidth Memory, and Samsung’s Wide I/O. Of the three, we’ve only seen HBM devices in-market, and those only on a relative handful of GPU models. That should change when AMD launches Vega later this year, but if JEDEC is planning for a DDR5, it obviously doesn’t think these alternate architectures are going to obviate the need for one in the near future. If the DDR5 standard is finished in 2018, it would likely launch in 2019-2020, but might not go mainstream until 2022-2023. Given how slowly computers evolve these days, it seems DRAM will be with us in one form or another for the foreseeable future.
I'm busy working on my blog posts. Watch this space!