A Peek At The State Of DDR5
Details of Micron’s DDR5 program were released today, though we are still some time from seeing it as a consumer product. They sampled their first RDIMMs back in January and today announced larger partnerships with Cadence, Montage, Rambus, Renesas and Synopsys. In perfect circumstances DDR5 will offer more than twice the effective bandwidth of DDR4, which we need now that core counts are climbing in HEDT processors from both AMD and Intel. In most cases you can definitely expect higher bandwidth at the same frequency, if not perhaps a doubling.
The design of the memory has changed from the previous generation, doubling the number of bank groups found in each chip on the module. The change doubles the number of banks in each module, which leads not just to higher density of memory but also makes communication significantly more efficient. This will also allow a doubling of burst lengths to 16 which also increases the bus efficiency and allows higher data rates. If that is not enough for you, how about two independent 40 bit channels per DIMM?
The bandwidth increase comes from a change in how the memory operates, such as how it locks banks when refreshing. With DDR4 the entire rank is locked when refreshing, however with DDR5 it is capable of refreshing one single bank per bank group. This means that during a refresh the other three banks in a group are usable, again a 75% boost will have an impressive effect on performance but not tripling it in most scenarios. Keep in mind that the doubling of bank groups is also in play here and that will also boost the performance. It will be interesting to see how quickly those dual 40 bit channels will be swamped by all these increases.
The start of the Technology Enablement Program and the partners involved indicate that DDR5 development is healthy and continuing as we would like to see. We don’t have any insight into when we might see product arrive, let alone processors and motherboards which will support them, but they are certainly getting closer to market every day. Take a look at the video for a brief look at what to expect from Micron.