AMD Instinct MI300X vs NVIDIA RTX A400 Comparison

Where Each One Wins

The benchmark database records a single shared test between these two accelerators, and the result is decisive. The AMD Instinct MI300X wins the only head-to-head benchmark, Geekbench OpenCL, by a massive margin. The NVIDIA RTX A400 wins no direct comparison in the recorded data, though its own benchmark suite shows strengths in specific workloads that are not tested against the MI300X.

The MI300X sits in the 100th percentile of all GPUs in the database, meaning no recorded accelerator scores higher on average. Its nearest rivals include the NVIDIA B200 (8% higher average score, which is why the MI300X remains at 100th percentile despite trailing that specific card), the NVIDIA H200 NVL (5% higher), the NVIDIA L40S (7.5% lower), and the NVIDIA RTX 6000 Ada Generation (10.7% lower). The MI300X is built for compute density, with a 5 nm process, 153,000 million transistors, and 192 GB of HBM3 memory. Its OpenCL score of 317,994 reflects raw throughput designed for large-scale parallel workloads, not interactive graphics.

The RTX A400, by contrast, sits in the 35th percentile of all GPUs. Its average benchmark score of 6,078 places it near the NVIDIA GeForce MX230 (0% delta), NVIDIA Quadro P2000 (0.5% higher), Intel Iris Pro Graphics 6200 (0.6% lower), and AMD Radeon 760M (1% higher). The A400 has its own recorded wins in DirectX 9 (87 points), DirectX 11 (37 points), DirectX 12 (27 points), DirectX 10 (32 points), G2D (899 points), G3D (5,983 points), and GPU compute (2,557 points), plus a Vulkan score of 22,237. These numbers indicate a low-power, compact workstation card for basic display output and light 3D acceleration, not a compute monster.

The use-case split is stark. The MI300X wins where massive memory pools and terabyte-scale bandwidth matter: training, inference, scientific simulation. The A400 wins where small size, low power draw, and multi-display output matter: office workstations, kiosk systems, basic CAD viewing. No recorded benchmark pits them directly in graphics workloads, so the A400's DirectX and Vulkan results stand alone, but the 1292% OpenCL delta leaves no ambiguity about compute headroom.

FAQ

Q: Which card has the higher Geekbench OpenCL score?

A: The AMD Instinct MI300X scores 317,994, while the NVIDIA RTX A400 scores 22,844. The MI300X leads by 1292%.

Q: Does the RTX A400 support DirectX?

A: Yes, the RTX A400 supports DirectX 12 Ultimate (12_2), OpenGL 4.6, and Vulkan 1.4. The MI300X has no recorded DirectX, OpenGL, or Vulkan support in the database.

Q: What is the memory capacity difference?

A: The MI300X has 192 GB of HBM3 with a 8192-bit bus and 5.32 TB/s bandwidth. The RTX A400 has 4 GB of GDDR6 with a 64-bit bus and 96.00 GB/s bandwidth.

Q: Which card has more shading units?

A: The MI300X has 19,456 shading units. The RTX A400 has 768 shading units.

Q: What are the power requirements?

A: The MI300X has a TDP of 750 W with a suggested power supply of 1150 W. The RTX A400 has a TDP of 50 W with a suggested power supply of 250 W.

Q: Which card has display outputs?

A: The RTX A400 has 4x mini-DisplayPort 1.4a outputs. The MI300X has no display outputs.

Head-to-Head Benchmarks

The only direct benchmark comparison in the database is Geekbench OpenCL. The MI300X delivers 317,994 points versus the A400's 22,844, a delta of 1292%. This is not a marginal gap; it is an order-of-magnitude difference in raw compute throughput. The MI300X's FP32 throughput is 81.72 TFLOPS, while the A400 manages 2.706 TFLOPS. Texture rate tells a similar story: 2,553.6 GTexel/s versus 42.29 GTexel/s.

The A400 does have its own benchmark suite that the MI300X cannot match because the MI300X lacks graphics APIs. In Passmark G3D, the A400 scores 5,983. In Passmark GPU compute, it scores 2,557. Its Vulkan score is 22,237. These numbers are modest by absolute standards, but they represent functional graphics capability. The MI300X has no recorded DirectX, OpenGL, or Vulkan scores, and its pixel rate is listed as 0 MPixel/s, meaning it cannot render frames for display.

The head-to-head data shows a compute accelerator versus a display adapter. The MI300X is 30 times faster in OpenCL, but it cannot output video. The A400 can drive four monitors, but its compute scores are 5,983 G3D points, which is below many integrated graphics solutions in the database. The nearest rivals for the A400 include the Intel Iris Pro Graphics 6200, which scores 6,117, and the AMD Radeon 760M, which scores 6,019. The A400 trails both by small margins, confirming its position as a low-end discrete option.

Specification Differences

The two cards differ in nearly every measurable specification. The MI300X uses a 5 nm process from TSMC with 153,000 million transistors on a 1017 mm² die, giving a transistor density of 150.4M per mm². The A400 uses an 8 nm process from Samsung with 8,700 million transistors on a 200 mm² die, for a density of 43.5M per mm². The MI300X has 19,456 shading units, 1,216 TMUs, and 0 ROPs. The A400 has 768 shading units, 24 TMUs, and 16 ROPs. The MI300X has no RT cores or tensor cores listed, while the A400 has 6 RT cores and 24 tensor cores.

Clock speeds reverse the expectation: the A400 runs at 1417 MHz base and 1762 MHz boost, while the MI300X runs at 1000 MHz base and 2100 MHz boost. Memory clocks also differ: the MI300X runs at 1300 MHz with 5.2 Gbps effective, the A400 at 1500 MHz with 12 Gbps effective. The MI300X's memory bandwidth (5.32 TB/s) dwarfs the A400's (96.00 GB/s), but the A400's GDDR6 has a higher effective data rate per pin.

Physical and interface differences are substantial. The MI300X is an OAM module with no power connectors and no display outputs, using PCIe 5.0 x16. The A400 is a single-slot card, 163 mm long and 69 mm tall, with 4x mini-DisplayPort 1.4a, using PCIe 4.0 x8. The MI300X has no listed dimensions, while the A400's compact size suits small form factor systems. The MI300X's suggested power supply is 1150 W; the A400's is 250 W. The A400 is marked as Active in production, while the MI300X has no production status listed.

Architecture Differences

The MI300X uses CDNA 3.0 architecture on the Aqua Vanjaram chip, designed for compute acceleration. The A400 uses Ampere architecture on the GA107 chip, designed for professional graphics. The MI300X has no graphics API support (DirectX, OpenGL, Vulkan all listed as N/A). The A400 supports DirectX 12 Ultimate (12_2), OpenGL 4.6, and Vulkan 1.4.

The MI300X's memory is HBM3 with a 8192-bit bus, meaning it moves data across a massive parallel interface. The A400 uses GDDR6 with a 64-bit bus. The MI300X has no ROPs, which explains its 0 MPixel/s pixel rate; rendering pixels is not its function. The A400 has 16 ROPs and a 28.19 GPixel/s pixel rate, allowing actual frame output.

The MI300X has 1,216 TMUs and a texture rate of 2,553.6 GTexel/s. The A400 has 24 TMUs and a texture rate of 42.29 GTexel/s. The MI300X's FP16 performance matches its FP32 at 81.72 TFLOPS (1:1 ratio), while the A400 also runs FP16 at 2.706 TFLOPS (1:1). Neither card lists separate tensor core throughput, but the A400's 24 tensor cores and 6 RT cores give it ray tracing and AI acceleration features absent from the MI300X's specs.

The MI300X belongs to the Instinct (MIx) generation, with the Radeon Instinct as predecessor. The A400 belongs to Workstation Ampere (Ax000), with Quadro Turing as predecessor and Workstation Ada as successor. Release dates differ by five months: the MI300X launched on 2023-12-05, the A400 on 2024-04-15. The MI300X has no listed launch MSRP, and neither does the A400.

The Verdict

The data points to two different products for two different jobs. The AMD Instinct MI300X is a compute accelerator with 192 GB of HBM3 memory, 5.32 TB/s bandwidth, and 81.72 TFLOPS of FP32 performance. Its OpenCL score of 317,994 places it at the 100th percentile of all GPUs in the database. The NVIDIA RTX A400 is a low-power workstation card with 4 GB of GDDR6, 2.706 TFLOPS of FP32, and a 35th percentile average score of 6,078.

Users who need compute density for AI training, large model inference, or scientific simulation should choose the MI300X. It has no display outputs, so it requires a separate graphics card for any visual output. Users who need a compact, single-slot card with four DisplayPort outputs for a multi-monitor workstation should choose the A400. It cannot handle heavy compute workloads, but its DirectX 12 Ultimate support, Vulkan 1.4, and 16 ROPs provide functional graphics acceleration.

The 1292% OpenCL gap is the defining metric. The MI300X is not merely faster; it is in a different performance class entirely. The A400's closest rivals in the database are all low-end or integrated parts, confirming its position. The MI300X's closest rivals are the NVIDIA B200, H200 NVL, L40S, and RTX 6000 Ada Generation, all high-end data center accelerators. The verdict is clear: the MI300X for compute, the A400 for display output. There is no crossover scenario where the A400 outperforms the MI300X in compute, and no scenario where the MI300X can replace the A400's display functionality.