Wednesday, March 22nd, 2017

DDR4 for Servers and High-End Desktop Systems


September 19, 2014, Intel Developer Forum, San Francisco—Geof Findley and Becky Loop provided an overview of the latest developments in memory technologies for high- performance systems. They described the various iA devices and compatibility with the latest DRAM devices and modules.

The first platforms to support DDR4 are the Xeon E5-2600 v3 family and Core processor extreme edition Core i7 CPUs. All of the server and workstation processors will support DDR4 in the future, including the Atom micro-server family. The tablet processors will continue to use LPDDR3 and DDR3. Future support for DDR4 memories will include other product families. Table 1 shows the various processor families and their currently supported memory types.

ddr4 table 1


Memory markets will be moving towards different sweet spots depending on the underlying memory types. LPDDR2 is staying at 1066 MHz in a x32 form with DIMM capacities of 1/2/4Gb. LLPDDR3 will be at 1600 and 1866 MHz in 4/8Gb for the first half of '14 and adding 4/6/8 Gb later in the year. LLPDDR4 will be at 3200 MHz and mostly in 8Gb formats.

DDR3/LPl-RS is capable of 1866, but the sweet spot is at 1600 and 4Gb densities. Higher capacities and speeds are possible but not widely used. DDR3 uDIMM and SoDIMM are capable of 8Gb and 16Gb capacities with the sweet spot at 8Gb. DDR3 RDIMM is capable of 32 or 64Gb but the sweet spot is 16Gb. DDR3 LRDIMM is also capable of 64Gb capacities, but will stay at 32Gb for the time being.

DDR4 at 1.2V is capable of 2400 KHz but most will be running at 2133 MHz. Densities of either 4 or 8Gb are possible with the majority of modules being 4Gb. In RDIMMs, DDR4 is going to be available in 16/32/64Gb configurations with 16Gb being the most widely used. The LRDIMMs will likely be at 32Gb.

Mobile DRAM is becoming a more variable market, dropping to 30 percent of all bit shipments earlier this year, but expected to stabilize at 40-45 percent in the longer term. DDR4 is starting out this year and is projected to gain a single digit market share this year, growing to 11 percent in '15 and half of all RAM bits by 2018.

The 4Gb density happened in '13 and will account for over three-fourths of all die shipments this year. 8Gb die will emerge later this year and will grow rapidly in mobile devices first. 8Gb and DDR4 will both become the primary configurations in '16. Servers will be the first high-end systems to use DDR4 later this year, and will ramp strongly next year. Desktops and laptops will see some use next year and will grow rapidly starting in '16.

Mobile DRAM is expected to stay with LPDDR3 through this year, being slightly more power efficient that LPDDR2, and 50 percent faster. LPDDR4 specs will be finalized this year and product will start shipping later this year. Wide I/O versions will appear next year, but will remain niche products for a while. DDR4 price premiums will remain through mid'16, dropping from 25 percent this year to 10 percent next year.

The advantages of DDR4 over DDR3 are in lower power and up to double the data rates. The device densities will grow from 4Gb to 8Gb for the DDR4 devices, and reliability is enhanced by the ability to add parity to the memory arrays. The higher densities and speeds are well suited for the high-performance 8-core processors, and the lower power and enhances RAS features are complementary for enterprise applications.

The DDR4 memories are key ingredients for cloud, HPC, networking and software-defined networks, storage arrays, and workstations. Although the devices currently carry a premium, the benefits of lower power and higher bandwidth provide headroom for future growth in memory requirements.

Many vendors, including Crucial, Kingston, Micron, Samsung, and SK Hynix are announcing support for DDR4 DIMMs in capacities of 8 and 16 GB. Compatible memories will be listed at as the come on the market. Modules for overclocking apps ar in test and evaluation, and some are achieving up to 3200 MT/s.

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