AMD is enabling CUDIMM DDR5 memory support with new AGESA updates & upcoming EXPO 1.2 tech, but only next-gen Ryzen CPUs will enable it.
DDR5 CUDIMM Support on AM5 Platforms Limited By IMC; Only Next-Gen AMD Ryzen CPUs Support It
Recently, there has been a lot of talk regarding AMD EXPO 1.2 and how it's bringing improved DDR5 memory support to AM5 platforms. It all started when ASUS launched its latest AGESA BIOS, which added EXPO 1.2 support on X870 series motherboards.
Soon after ASUS's release, more details for EXPO 1.2 were shared, which suggested CUDIMM & CSODIMM support, along with other nifty enhancements that will lead to wider compatibility with next-gen modules and kits. The technology also enables Ultra-Low Latency DDR5 kit support, which will further reduce AM5's latency figures.
Now, MSI's engineer, Toppc, has revealed a crucial detail that should've been known by now. The thing is that AMD's EXPO 1.2 or AGESA BIOS updates won't magically enable CUDIMM support for existing CPU lineups.
The 1.2 CKD setting only defines whether CKD is enabled. If the CPU IMC doesn't support it, it still won't be supported. Setting it to enabled won't prevent support. You can refer to the hardware information; this is a secret the motherboard manufacturer didn't disclose.
Toppc - MSI Motherboard Engineer & In-House Overclocker
Based on Toppc's comments, while the support is being added to existing AM5 motherboards to expand to CUDIMM memory, the actual usability of those DDR5 modules will only be possible with CPUs that have CUDIMM support integrated within their IMC. Current-Gen AMD Ryzen CPUs feature an IMC that doesn't have CUDIMM functionality baked in.
CUDIMM "Bypass Mode" For Current-Gen Ryzen CPUs
These processors will support CUDIMM memory, but rather than running them at their advertised speeds, they will go through a "Bypass" mode, which effectively pushes the controller to run these modules at ~6000 MT/s (3000-3600 MHz effective), which will allow the motherboards to boot on CUDIMM memory modules.
The same is true on older Intel platforms, so whether you have a CUDIMM DDR5 memory or an AM5 board that supports CUDIMM, you won't see the benefits until or unless you have an AMD Ryzen CPU, which also offers support through the IMC. That CPU will only arrive with the next-gen Ryzen lineup, based on the Zen 6 architecture. And that's why motherboard makers and memory vendors are actively working to add CUDIMM support for AM5 platforms, but that is the direction AMD is headed in.
Additionally, ASUS is also teasing EXPO 1.2 support on older 600-series motherboards, such as X670 and B650 series. Meanwhile, the company has also released EXPO 1.2 BIOS support for its B850 motherboards. The BIOS still needs tuning for older motherboards, but it's nice that updated EXPO support will be brought to the first generation of AM5 motherboards, further showcasing the longevity that the platform has on offer for PC builders.
About the author: A Software Engineer by training and a PC enthusiast by passion, Hassan Mujtaba serves as Wccftech's Senior Editor for hardware section. With years of experience in the industry, he specializes in deep-dive technical analysis of next-generation CPU and GPU architectures, motherboards, and cooling solutions. His work involves not only breaking news on upcoming technologies but also extensive hands-on reviews and benchmarking.
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