Mysterious MI300C AI Accelerator Spotted in Linux Patches, Up to 96 Zen4 With 128GB of HBM3

AMD launched its MI300 series of AI Accelerators which include the MI300A and the MI300X. Presumably, the X refers to an all-out GPU packing 304 CUs across 8 chiplets. Similarly, the ‘A‘ in MI300A should put it under the category of APUs.

Today’s leak revolves around Linux patches that have confirmed the existence of a third, CPU-only MI300C variant. The ‘C’ here should place it under the umbrella of Instinct MI Accelerator CPUs. But there’s nothing fancy here, since this CPU is technically an EPYC Genoa with HBM3.

MI300C Spotted in the Wild

Coelacanth Dream discovered a third variant, the MI300C in the Linux EDAC driver. The MI300C boasts up to 96 Zen4 cores and packs 128GB of HBM3, that we already know. This configuration equates to 12 CCDs, much like the EPYC 9654. Since AMD has not, yet, announced this CPU, we are not sure about its place in the market.

AdoredTV has already leaked quite a bit regarding AMD’s Instinct MI Accelerators. This leak also included the MI300C. However, as AMD has not disclosed this offering, it may be reserved for the Chinese market, but that’s just speculation.

MI300 Series Overview

If you are confused regarding the configuration of these AI Accelerators, here’s a small overview. The MI300 series features 3 products including:

  • MI300A (CPU+GPU)
  • MI300X (GPU Only)
  • MI300C (CPU Only)

The MI300A features 6xXCDs for the GPU (Based on CDNA3). Each XCD packs 40 Compute Units so the total package amounts to 228 CDNA3 Compute Units. For the CPU solution, we see 3xCCDs based on Zen4, where each CCD has 8 cores for a total of 24 Zen4 cores. Both the GPU and CPU share 128GB of HBM3 (8x16GB stacks).

MI300 Diagram | SemiAnalysis

The MI300X ships with 8 XCDs (40 CU each), summing up to a total of 304 CUs. This package does not have a CPU and is primarily a graphics solution.

Last, but not least, the MI300C is like an EPYC 9654 with 8xHBM3 stacks. This acts as an all-in-one for intensive CPU-oriented tasks.

EPYC 9654 CPU With 12 CCDs | AMD

AMD confirmed during its earnings call that these accelerators are en route to clients. They are expected to hit the market by Q4 2023. We expect to hear more from AMD regarding the MI300C until then.


Abdullah Faisal

With a love for computers since the age of five, Abdullah has always sought to delve into the depths of information, and uses it as his guiding light. He believes success is of utmost importance as history is written by the victor.