In this article
AMD publishes 432 GB HBM4 for the MI455X EAM platform accelerator. Direct liquid cooling and system qualification are part of the deployment boundary.
Read the EAM and Helios platform context
The MI455X product specification identifies a CDNA 5 accelerator with 432 GB HBM4, an EAM form factor and direct liquid cooling in the Helios platform context. This is not a consumer Radeon card or an ordinary add-in PCIe board. A capacity figure without the host and thermal platform is an incomplete deployment description. Public specifications establish the published design; they do not establish delivery timing, available supplier inventory or an installed configuration at Retrivium. Those questions need separate evidence for a concrete system.
| Variant | Local memory, GB | Memory type | Published board power, W |
|---|---|---|---|
| MI455X EAM platform | 432 | HBM4 | Not verified |
The product or OEM specification establishes the configuration: manufacturer source.
Treat software support as a versioned combination
CDNA 5 branding does not validate an arbitrary ROCm package or serving wheel. At evaluation time, check the exact device, operating system, firmware, driver and runtime combination in current primary documentation. Then verify the model architecture, precision and attention implementation in the intended framework. General framework names on a product page do not certify every checkpoint or quantization path. Preserve the accepted package versions and compare output against a reference before measuring speed; unresolved kernel or runtime support should remain explicitly unresolved.
The software boundary is documented in the inference compatibility reference.
Separate accelerator HBM from rack totals
The 432 GB figure belongs to the published accelerator specification. A Helios system or rack can contain multiple accelerators, but multiplying capacity does not create one local memory space for a model. The serving engine needs an explicit distribution strategy with known device placement and collective communication behaviour. Budget weights, KV cache and workspaces on the devices that actually own them. HBM4 capacity and published bandwidth are not a token-throughput formula, so a platform comparison requires a fixed request distribution and service objective.
Do not transfer Radeon HIP rendering assumptions
MI455X is an Instinct CDNA compute accelerator. Current Cycles HIP documentation establishes an RDNA hardware baseline; the existence of ROCm compute software does not turn CDNA into a documented Radeon rendering device. This article therefore makes no claim of current Cycles HIP eligibility for MI455X. If a specialised compute renderer or another engine is considered, obtain its exact device support evidence and validate a scene. LLM framework support alone says nothing about material compatibility, graphics features or the correctness of a rendered frame.
Renderer requirements are separate in the Cycles GPU manual.
Keep platform readiness distinct from a published design
An acceptance record for an actual MI455X deployment should include the OEM system, liquid-cooling configuration, firmware and supported power settings. Evaluate sustained workloads, error reporting and restart recovery only in that qualified environment. Keep published specification, verified availability and measured workload support as separate statuses. The catalogue is informational: it does not imply that Retrivium has installed Helios hardware or completed OpenRouter approval. New primary documents and real system results can refine the profile without rewriting an architecture announcement into an operational service promise.
Related reading: RAM and VRAM and a reproducible inference benchmark. GPU catalogue records the scope, model variants and unresolved specifications.