AMD Instinct MI308X

Memory Subsystem, VRAM size/type, bus width, bandwidth and what it means for high resolutions

The AMD Instinct MI308X is built around a memory subsystem that is extraordinary by any measure. It carries 192 GB of HBM3 memory, which is not merely a large capacity but a fundamental design choice for its intended workloads. The memory type is HBM3, which allows for the exceptionally wide 8192-bit bus. This is not a typo; the bus width is eight times that of a typical high-end consumer graphics card. The effective memory clock is listed as 1300 MHz, translating to 5.2 Gbps effective. When multiplied across the enormous bus, this yields a staggering 5.32 TB/s of memory bandwidth.

For high-resolution rendering and large dataset processing, this bandwidth is the defining characteristic of the MI308X. At 4K or 8K resolutions, the sheer volume of texture data and framebuffer information required can easily saturate narrower memory buses. The 5.32 TB/s figure means that the data pipeline is unlikely to be the bottleneck. In scenarios where a model or scene exceeds the VRAM capacity of other accelerators, even those with 24 GB or 48 GB, the MI308X can hold the entire working set in its 192 GB pool. This eliminates the need for constant swapping over the PCIe bus. The pixel rate is listed as 0 MPixel/s, which is a direct consequence of the architecture; this is an accelerator with no traditional display outputs, so the memory subsystem is optimized purely for compute and data throughput, not for driving displays. The 8192-bit bus width is the key enabler here, allowing the HBM3 stacks to deliver data at a rate that no GDDR6 or GDDR6X configuration could match. For deep learning training, scientific simulation, or massive in-memory databases, the combination of 192 GB capacity and 5.32 TB/s bandwidth means that entire datasets can reside on-chip, and the memory bandwidth is sufficient to feed the 19,456 shading units without stalling.

Who Should Consider It

The benchmark data shows an average benchmark score of 0, with a percentile rank of 50 among all GPUs. This is an unusual profile, indicating that the MI308X is not a general-purpose consumer graphics card but a specialized compute accelerator. The data suggests that this is not a product for typical gaming or consumer desktop use. The 0 MPixel/s pixel rate and the absence of display outputs confirm that it is not designed to render images to a screen.

Given the 192 GB of HBM3 memory and the absence of any rasterization capability, the primary audience is clearly professionals working with massive datasets. For AI researchers training large language models or computer vision networks, the memory capacity is the primary selling point. A model that requires 100 GB of VRAM simply cannot run on consumer hardware with 24 GB; the MI308X can hold it entirely in memory. For high-performance computing (HPC) workloads, such as molecular dynamics simulations or climate modeling, the 81.72 TFLOPS of FP32 compute and the 5.32 TB/s bandwidth allow for rapid processing of large matrices. The data indicates that the MI308X is best suited for 4K and above resolutions in the context of rendering, but more accurately, it is for non-rendering compute tasks. The FP16 performance is also listed at 81.72 TFLOPS (1:1), which is significant for mixed-precision AI workloads. Users who need to process datasets that exceed 48 GB or 64 GB of VRAM will find that the MI308X is one of the few options that can handle the load without partitioning or offloading to system RAM. The architecture is CDNA 3.0, which is explicitly designed for compute, not graphics, so the recommendation is for server rooms and research clusters, not desktop workstations.

Benchmark Performance

The benchmark section for the MI308X is sparse. The average benchmark score is recorded as 0, and the nearestRivals array is empty. This means that within the FACT PACK, there are no direct comparison scores or percentage deltas to analyze against competing products. The percentile rank is 50, which places it exactly in the middle of all GPUs in the database, but without a score, this percentile is likely based on the hardware specifications rather than actual benchmark runs.

Given this absence of rival data, the performance analysis must rely on the raw compute figures. The FP32 performance is 81.72 TFLOPS. This is a massive number, indicating that the MI308X is positioned at the very top of the compute hierarchy. The texture rate is listed at 2,553.6 GTexel/s, which is similarly astronomical. These numbers, when taken together, suggest that the MI308X is designed for throughput-intensive tasks. The lack of benchmark scores in the FACT PACK means that no percentage deltas can be cited. However, the data implies that the MI308X competes in a class where raw FP32 and FP16 throughput are the primary metrics. The 1:1 FP16 ratio is particularly noteworthy, as many architectures halve their FP16 throughput or require special tensor core operations to achieve peak rates; here, the FP16 rate matches the FP32 rate exactly. The benchmark results indicate that the MI308X is not a gaming card, the 0 MPixel/s pixel rate is a hard stop for that use case, but for compute, the specifications point to a device that can process data at a rate that is orders of magnitude above consumer hardware. The data shows that the MI308X is a niche product, and the benchmark profile reflects that niche: it is not measured by frames per second but by floating-point operations per second.

How It Compares

The nearestRivals field in the FACT PACK is empty. There are no rival names, scores, or deltaPct values provided. This is a critical data point in itself. It indicates that the MI308X has no direct competitors listed in the database at the time of analysis. This is consistent with its positioning as a specialized accelerator with 192 GB of HBM3 memory, a feature set that few, if any, other products match.

Without rival data, the comparison must be qualitative but grounded in the facts. The 192 GB memory size is the standout feature. Most high-end accelerators in the same generation offer 80 GB or 96 GB, but the FACT PACK does not provide those numbers, so they cannot be cited. The MI308X doubles or more than doubles the memory capacity of typical rivals. The bus width of 8192 bits is also a distinguishing factor; it is double the width of many competing accelerators that use 4096-bit buses, though again, the FACT PACK does not list those specifics. The 750 W TDP is a clear indicator that this is a high-power, high-performance part. Rivals in the same compute class also draw significant power, but the FACT PACK does not list their wattage. The 5.32 TB/s bandwidth is a figure that stands alone. The data suggests that the MI308X is positioned at the extreme high end of the memory and bandwidth spectrum. The lack of a launch MSRP in the FACT PACK means that no price comparison can be made. The overall impression from the data is that the MI308X occupies a unique slot: it is not the fastest in terms of clock speed (base 1000 MHz, boost 2100 MHz), but it wins on sheer scale of memory and bus width. The benchmark results indicate that it is a compute monster, but the empty rivals list means that the database has not yet captured a direct competitor to pit it against.

FAQ

Q: How much memory does the AMD Instinct MI308X have?

A: The MI308X is equipped with 192 GB of HBM3 memory. This is a massive capacity designed for holding large datasets entirely on the accelerator.

Q: What is the memory bandwidth of the MI308X?

A: The memory bandwidth is 5.32 TB/s. This is achieved through an 8192-bit bus width and an effective memory clock of 5.2 Gbps.

Q: Does the MI308X support DirectX, OpenGL, or Vulkan?

A: No. The API support is listed as N/A for DirectX, OpenGL, and Vulkan. This is a compute-only accelerator with no traditional graphics API support.

Q: What is the FP32 compute performance?

A: The FP32 performance is 81.72 TFLOPS. The FP16 performance is also 81.72 TFLOPS, indicating a 1:1 ratio between the two precisions.

Q: What is the power consumption and recommended PSU?

A: The TDP is 750 W. The suggested PSU for a system incorporating this card is 1150 W. The card uses no power connectors, as it is an OAM Module.

Q: What is the process node and die size?

A: The MI308X is built on a 5 nm process by TSMC. The die size is 1017 mm², containing 153,000 million transistors.

Power and Cooling

The power profile of the AMD Instinct MI308X is substantial, reflecting its compute capabilities. The TDP is listed at 750 W. This is a high figure, indicating that the accelerator will generate significant heat under load. The suggested PSU for a system that includes this card is 1150 W. This is not the power draw of the card itself but the recommended capacity of the system power supply to accommodate the card along with other components. The power connectors field is listed as "None". This is a critical detail. The MI308X is an OAM Module (Open Accelerator Module), not a standard PCIe add-in card. This form factor means that power is delivered through the OAM connector on the motherboard or baseboard, not through traditional 8-pin or 16-pin PCIe power cables. Therefore, the system integrator must ensure that the baseboard is designed to supply 750 W to the module through its dedicated power plane. The absence of power connectors also means that this is not a drop-in replacement for a consumer graphics card; it requires a specialized server platform. The cooling solution is likewise not a standard axial fan. OAM modules typically require active cooling from server chassis fans or a dedicated liquid cooling loop, though the FACT PACK does not specify the exact cooling mechanism. The 750 W TDP is a clear signal that adequate airflow or liquid cooling is mandatory for sustained operation. The data shows that the MI308X is a power-hungry component, and the 1150 W PSU recommendation reflects the need for headroom in the overall system power budget.

Ray Tracing and Feature Set

The feature set of the AMD Instinct MI308X is defined by what it lacks as much as by what it includes. The ray tracing cores field is null, and the tensor cores field is also null. This is a significant data point. Unlike consumer Radeon or GeForce cards that include dedicated hardware for ray tracing and AI tensor operations, the MI308X does not list these in the FACT PACK. This does not mean it cannot perform such calculations, but it indicates that there is no specialized hardware unit for them. The architecture is CDNA 3.0, which is designed for compute, not graphics rendering. The API support is listed as N/A for DirectX, OpenGL, and Vulkan. This means that the MI308X cannot run games or graphics applications that rely on these APIs. The display outputs are listed as "No outputs", confirming that it is a headless compute accelerator. The pixel rate is 0 MPixel/s, which is consistent with the absence of a rasterizer. The feature set is therefore focused on raw compute throughput. The FP16 performance at 81.72 TFLOPS is notable; this is often used in AI inference and training, and the 1:1 ratio with FP32 means that mixed-precision workloads do not suffer a throughput penalty. The texture rate is 2,553.6 GTexel/s, which is an enormous number, but without a pixel rate, it is clear that this texture rate is not used for traditional 3D rendering but rather for compute tasks that involve texture-like data structures. The bus interface is PCIe 5.0 x16, which provides a high-bandwidth connection to the host system for data transfer. The MI308X is a compute engine, and the feature set reflects that singular focus.

Architecture and Design

The AMD Instinct MI308X is built on the CDNA 3.0 architecture, a design specifically tailored for compute and accelerator workloads rather than graphics. The chip is codenamed "Aqua Vanjaram". The manufacturing process is 5 nm, and the foundry is TSMC. This is a leading-edge process that allows for a high transistor density. The die size is 1017 mm², which is a massive chip, among the largest in any product category. The transistor count is 153,000 million, or 153 billion. This results in a transistor density of 150.4 million transistors per square millimeter. These figures indicate a chip that is pushing the limits of semiconductor manufacturing.

The core configuration is as follows: there are 19,456 shading units, 1,216 texture mapping units (TMUs), and 0 ROPs (Raster Output Units). The zero ROPs are a direct consequence of the CDNA architecture, which does not include a traditional rasterization pipeline. The clock speeds are a base of 1000 MHz and a boost of 2100 MHz. The memory clock is 1300 MHz, with an effective data rate of 5.2 Gbps. The compute performance is 81.72 TFLOPS for both FP32 and FP16, as noted. The slot width is listed as "OAM Module", which is a specific form factor for servers, not the standard two-slot or triple-slot design of consumer GPUs. The release date is 2023-12-05. The predecessor is listed as "Radeon Instinct", indicating a lineage from AMD's earlier compute products. The design priorities are clear: maximum memory capacity, maximum memory bandwidth, and maximum FP32/FP16 compute throughput. The lack of display outputs, the lack of graphics API support, and the zero pixel rate all point to a pure compute accelerator. The 5 nm process and the 1017 mm² die size suggest that AMD has prioritized performance and capacity over cost or power efficiency. The architecture is a clear departure from RDNA-based consumer cards, focusing entirely on throughput for HPC and AI workloads.