AMD is preparing support for DDR5 in CUDIMM format on AM5 via new AGESA microcodes and the EXPO 1.2 profile. According to discussions with manufacturers, complete activation will however depend on the integrated memory controller of the next Ryzen. BIOS updates will still improve compatibility and latency on many AM5 motherboards. Here’s where we are and what it changes for future configurations.
EXPO 1.2 and CUDIMM DDR5 on AM5: quick update
AMD activates support for DDR5 memory in CUDIMM format via new AGESA updates and the future EXPO 1.2, but only the next generation Ryzen will be able to fully exploit it.
DDR5 CUDIMM support on AM5 limited by BMI; only the next AMD Ryzen manage it natively
There has been a lot of talk recently about EXPO 1.2 and the improved DDR5 support on AM5. It all started with the latest AGESA BIOS released by ASUS, which adds EXPO 1.2 to the X870 series motherboards.
Shortly after ASUS’ release, more details about EXPO 1.2 emerged, mentioning CUDIMM and CSODIMM compatibility, as well as various useful improvements intended to expand support for upcoming modules and kits. The technology also targets very low latency DDR5 kits, which will further reduce the latency figures observed on AM5.
An MSI engineer, Toppc, however, provided an essential clarification that should have been obvious: EXPO 1.2 or an AGESA update will not magically make current CPU ranges compatible with CUDIMMs.
The CKD 1.2 setting only defines whether CKD is enabled. If the CPU BMI does not support it, compatibility will remain absent. Enabling it does not block support. You can refer to the material information; It’s a secret that the motherboard manufacturer hasn’t divulged.
Toppc – Engineer MSI motherboards & internal overclocker
According to Toppc, even if AM5 motherboards receive access to CUDIMM memory at the BIOS level, the effective use of these DDR5 modules will only be possible with CPUs whose IMC integrates CUDIMM compatibility. Current AMD Ryzen CPUs have an IMC without this feature.
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CUDIMM “Bypass” mode for current Ryzen
These processors will accept CUDIMMs, but instead of reaching the advertised frequencies, they will go through a “Bypass” which pushes the controller to around 6000 MT/s (3000-3600 MHz effective), which allows motherboards to boot with CUDIMM modules.
We observe the same thing on old Intel platforms: whether you use DDR5 CUDIMM or an AM5 motherboard displaying compatibility, the benefits will only appear with an AMD Ryzen CPU whose IMC also supports this standard. The CPU in question will only arrive with the next generation Ryzen, based on the Zen 6 architecture. This is why motherboard manufacturers and memory brands are already working to add CUDIMM support on AM5: this is the trajectory taken by AMD.
ASUS is also teasing EXPO 1.2 support on older 600 series motherboards, like the X670 and B650. At the same time, the brand has published EXPO 1.2 BIOS for its B850s. BIOSes still need tweaking on older models, but seeing EXPO updated on the first generation of AM5 cards confirms the longevity of the platform for PC builders.
