JEDEC Extends DDR5 Memory Spec to 8800 MT/S, Adds Anti-Rowhammer Features

When JEDEC released its DDR5 specification back in 2020, the standard setting organization defined precise specs for modules with speed bins of up to 6400 MT/s, while leaving the spec open to further expansions with faster memory as technology progressed. Now, a bit more than three-and-a-half years later, and the standards body and its members are gearing up to release a faster generation of DDR5 memory, which is being laid out in the newly updated JESD79-JC5 specification. Diving in, the new specification outlines settings for memory chips with data transfer rates up to 8800 MT/s. This suggests that all members of the JESD79 committee that sets the specs for DDR5 - including memory chip makers and memory controller designers - agree that DDR5-8800 is a viable extension of the DDR5 specification both from performance and cost point of view. In exchange for systems willing to wait a bit longer for a result, the new spec improves the standard's peak memory bandwidth by 37.5%. This of course is just the timings set in the JEDEC specification, which is primarily of concern for server vendors. So we'll have to see just how much harder consumer memory manufacturers can push things for their XMP/EXPO-profiled memory. Using this information, memory controllers can then determine if a memory row has been excessively activated and is at risk of causing a neighboring row's bits to flip, at which point they can back off to let the neighboring row properly refresh and the data re-stabilize. PASR is primarily aimed at power efficiency for mobile memory to begin with, and as a refresh-related technology, presumably overlaps some with rowhammer - be it a means to attack memory, or an obstruction to defending against rowhammer.