The JEDEC Solid State Technology Association has finally concluded the specification for DDR5 SDRAM, it announced Tuesday. Like DDR4 and its predecessors, DDR5 aims to drive memory density and frequency to new heights.
DDR5 RAM sticks will have the same number of pins, 288, as DDR4 DRAM modules. The pin layout, however, is different. That means you won't be able to use DDR5 modules on a DDR4 slot. As expected, the new design commands a fresh home, which in this case will be a DDR5 slot.
DDR4 employs a 16-bank structure with four bank groups. DDR5's improved design comprises 32 banks distributed over eight bank groups. The burst length on DDR5 is doubled from eight to 16. DDR5 comes equipped with the Same Bank Refresh function (SBRF), allowing the PC to tap into other banks while one is operating.
DDR5 enables up to four times higher capacity per module in comparison to DDR4. DDR4 modules handle 16 Gbit chips and max out at 32GB. DDR5, on the other hand, can leverage 64 Gbit chips, which pushes the maximum capacity on a single module from 32GB up to a whopping 128GB.
Things look even brighter on the enterprise side. DDR5 supports die stacking, so memory vendors can potentially stack up to 16 dies onto one chip. As a result, a single Load-Reduced DIMM (LRDIMM) can come with a capacity of 4TB.
DDR5 vs DDR4
| Header Cell - Column 0 | DDR5 | DDR4 |
|---|---|---|
| Data Rates | 3,200 - 6,400 MTps | 1,600 - 3,200 MTps |
| Device Densities | 8Gb - 64Gb | 2Gb - 16Gb |
| Max UDIMM Size | 128GB | 32GB |
| Bank Groups (BG) / Banks | 8 BG x 2 banks (8Gb x4/x8), 4 BG x 2 banks (8Gb x16), 8 BG x 4 banks (16-64Gb x4/x8), 4 BG x 4 banks (16-64Gb x16) | 4 BG x 4 banks (x4/x8), 2 BG x 4 banks (x16) |
| Burst Length | BL16, BL32 (and BC8 OTF, BL32 OTF) | BL8 (and BL4) |
| REFRESH Commands | All bank and same bank | All bank |
| VDD / VDDQ / VPP | 1.1 / 1.1 / 1.8 | 1.2 / 1.2 / 2.5 |
In addition to increasing module capacity fourfold, DDR5 serves up a healthy boost in memory bandwidth over DDR4. For comparison, the official data rates for DDR4 span from 1,600 MTps to 3,200 MTps. DDR5 starts where DDR4 left off, ranging from 3,200 MTps - 6,400 MTps -- double the maximum bandwidth of DDR4.
JEDEC's specifications are a good reference point, but the best RAM vendors have been known to push the limits on their own. Nowadays, you can find DDR4 memory kits with data rates up to 5,000 MTps, so you can expect DDR5 memory kits to eventually exceed the 6,400 MTps mark. With that in mind, SK Hynix's ambitious goal to release a DDR5-8400 module seems feasible.
Keeping with tradition, DDR5 also brings operating voltage improvements. A lower operating voltage means better power efficiency. DDR5 modules will run at 1.1V, as opposed to 1.2V on DDR4
JEDEC has taken voltage regulation a step further. One of the motherboard's duties is regulating voltage for each individual RAM stick. This will be a thing of the past with DDR5. DDR5 modules will feature their own voltage regulators integrated on the sticks. This will take the load off the motherboard but will likely drive up price.
DDR5 Release Date
On Tuesday, Micron also launched its Technology Enablement Program to facilitate the transition to DDR5. The program gives approved partners early access to technical information and support, as well as DDR5 components and samples.
DDR5 adoption should commence in 2021. Server platforms will likely be the first to welcome DDR5 before the standard arrives on consumer platforms.
On the Intel front, Sapphire Rapids CPUs will come with DDR5 support. As for AMD, the chipmaker's upcoming fourth-generation EPYC (codename Genoa) processors should also do DDR5.
