MI300X VS MI325X: CHOOSING AN AMD PLATFORM

MI325X adds memory capacity and bandwidth to the MI300X comparison, alongside a higher peak board power rating. The buying decision needs a qualified server and a validated ROCm workload. Start with the constraint you need to remove, then compare complete configurations.

Manufacturer specifications and original deployment analysis · No application benchmark is implied

The relevant differences are per accelerator

AMD lists MI300X with 192 GB of HBM3 and MI325X with 256 GB of HBM3e. Both are OAM modules in the CDNA 3 family. They require a suitable server platform, rather than a conventional add-in slot.

AMD's MI300X specifications and MI325X specifications are the sources for this table. These are product ratings. They do not describe the condition of a particular used module or the measured performance of an application.

The capacity increase is 64 GB per accelerator, or one-third of MI300X's stated capacity. The bandwidth increase is approximately 13.2%, using the published peak figures. Neither percentage should be presented as an application speedup.

Specify module and server quantities separately in a sourcing request. “Eight MI325X” could describe a set of modules or the accelerators inside a complete server. The baseboard, thermal assemblies and host components must appear in the included-component list.

Additional memory is valuable when the workload can use it

Begin with an allocation budget for the intended job. Separate weights from cache, activations and runtime buffers. Record the numerical format for each component. A weight-precision setting does not establish the KV cache's storage precision.

Consider a hypothetical 100-billion-parameter model stored at two bytes per parameter. Its idealized weights occupy 200 decimal GB. That is larger than MI300X's stated 192 GB, before other allocations. MI325X provides more stated capacity, but the remaining budget must still be validated.

The useful next step is a real test of that model artifact and serving configuration. Check peak memory during loading as well as steady execution. Run the intended context length and concurrency. A configuration can pass a small demonstration and fail when the working set grows.

For models that already fit comfortably in 192 GB, identify what the extra space would change. It might allow more cached tokens, a different batch or another job on the server. If none of those changes are useful, the additional memory may not address the limiting factor.

For a distributed workload, do not assume aggregate HBM behaves like one large local allocation. Ask the application team how parameters and intermediate data are distributed. Include any replicated buffers in the budget. The number of accelerators needed for memory is not automatically the number needed for throughput.

Keep capacity decisions separate from quantization decisions

Quantization may create another viable configuration, but it changes the evaluation. Compare output quality against a defined baseline, using representative requests. Record the model revision and quantization method so that a smaller artifact is not mistaken for the same software configuration.

Decide whether the team is prepared to maintain that configuration. If the value of a lower-memory proposal depends on a custom conversion pipeline, include that operational work. A hardware comparison should not hide a software project.

A shared OAM label does not establish a supported upgrade

MI325X's higher peak board power makes the server review essential. Ask the OEM to confirm the exact module, baseboard, firmware and cooling combination. Do not assume an existing MI300X server can accept MI325X merely because both modules use OAM.

For eight accelerators, multiplying the published ratings gives 6,000 W for MI300X modules and 8,000 W for MI325X modules. These are accelerator-only sums. They are not complete server or rack power budgets, and they are not measured energy consumption.

Use the OEM system specification for facility planning. Include the expected operating configuration and any redundancy requirements. Have the facility operator review the proposed installation before shipment, especially where a replacement changes the thermal or electrical load.

Ask whether the offer includes the thermal assemblies needed for the qualified configuration. Identify any missing mounting parts or service tools. A bare module's price should not absorb unpriced assumptions about the host platform.

For a complete server, request the host memory, CPU configuration, storage and networking details. These components affect whether the accelerator can be kept busy. A comparison limited to HBM capacity may miss the stage that limits the actual application.

Validate a specific ROCm configuration

ROCm support is a combination of hardware, operating system, driver and software release. Write those versions into the evaluation plan. Add the framework build and container digest if applicable. The statement “runs PyTorch” is too broad to establish a reproducible deployment.

AMD's release-specific compatibility matrix separates supported combinations and includes footnotes. Use the matrix for the selected release rather than an undated list of supported GPUs. The ROCm 7.2.2 matrix is one versioned reference, not a recommendation to choose that release over newer options.

Read the release notes as well. For example, the 7.2.2 notes include an MI325X KVM SR-IOV driver restriction. That illustrates why a hardware name in a support list is not the end of the check. Validate any virtualization plan against the selected release's specific requirements. Source: versioned ROCm release notes

CUDA code is not automatically an AMD deployment

Inventory dependencies before deciding how much migration work is needed. Separate framework-level code from custom GPU kernels and vendor-specific libraries. Identify binary extensions that would need another build. Ask who will own those changes after the initial port.

AMD's HIPIFY documentation describes tooling that helps translate CUDA code. It also explains that unsupported libraries and architecture-specific optimization may require manual work. A translated build still needs correctness testing and performance evaluation. Source: HIPIFY capabilities and limitations

Set two separate acceptance gates for a migration. First, establish that the application produces acceptable results. Second, establish that it meets the performance and operating targets. Passing the first gate should not be presented as evidence for the second.

Retain the working baseline and a representative test set. Include difficult cases, not only the example that ports most easily. If a proposed configuration depends on a model-specific optimization, document that dependency alongside the hardware recommendation.

Make the comparison answer a buying question

Choose one target outcome before testing. For an interactive service, define the request mix and latency limit. For batch inference, define the dataset and completion deadline. For training, define the effective batch and quality target.

Run both configurations with documented software and power settings. If different optimized stacks are used, state that difference explicitly. Keep the first comparison simple enough to explain which variables changed.

For inference, separate time to first token from token generation rate. Track completed requests and failures. Include the largest supported context and the desired simultaneous load. An attractive average should not conceal a configuration that fails the acceptance target.

For training, measure useful progress rather than theoretical tensor capacity. Record any change to checkpointing, precision or parallelism. Those choices can affect both memory and throughput, so they belong beside the result.

Compare energy only when the measurement boundary is clear. Accelerator telemetry and rack input power are different observations. If energy efficiency matters, define whether the result covers GPUs, a server or the wider installation. Do not derive energy-per-job from peak board power alone.

Turn a used offer into a reviewable configuration

Request the actual module identifiers and OEM part numbers. Match them to photographs and the seller's test records. Ask whether the records cover every offered module or a sample from the lot.

The seller should state the test software, date and system configuration. Ask for the conditions under which the reported result was obtained. Keep any exceptions visible. A generic statement of “fully tested” does not identify the checks performed.

Compare commercial terms only after the technical scope matches. Separate any integration work from the accelerator line item. Ask the seller to document what happens if the delivered configuration differs from the agreed offer.

Cardinal reviews the documents supplied by sellers. It does not claim to test these modules or certify an application migration. State the evidence your team needs in the quote request so that gaps can be resolved before acceptance.

Questions buyers ask about MI300X and MI325X

Does MI325X have twice the memory of MI300X?

No. The published capacities are 256 GB and 192 GB per accelerator. MI325X adds 64 GB, a one-third increase.

Is MI325X a drop-in replacement for MI300X?

Do not assume that. Ask the server OEM to confirm the exact configuration, including power, cooling and firmware. The shared module category is not an upgrade approval.

Will my CUDA application run unchanged?

That depends on its dependencies and deployment path. Inspect the framework build, custom kernels and libraries. Porting tools can help, but correctness and performance still require validation.

Should I choose MI325X for the larger memory alone?

Only if the additional memory helps meet a defined workload requirement. Compare a working MI300X proposal with a working MI325X proposal, including the server and software work.

What should I include in a sourcing request?

Specify the model, module or server quantity, destination and desired condition. Add the intended ROCm configuration and workload. State whether the offer must include a qualified complete server.

Review the MI300X reference and MI325X reference, then use the used hardware checklist to compare offers.