AMD Instinct MI455X vs NVIDIA RTX A400 Comparison

Head-to-Head Benchmarks

The recorded data contains no direct head-to-head benchmark comparisons between the AMD Instinct MI455X and the NVIDIA RTX A400. The head-to-head benchmark array is empty, and the AMD Instinct MI455X has no individual benchmark scores, no average benchmark score, and no nearest rivals listed in the database. The NVIDIA RTX A400, by contrast, has a complete set of nine benchmark results across Geekbench and Passmark tests.

The NVIDIA RTX A400 delivers its strongest recorded result in Geekbench OpenCL with a score of 22,844, closely followed by Geekbench Vulkan at 22,237. These two scores represent the compute-oriented workloads in the database. In Passmark tests, the A400 shows a different distribution: DirectX 9 scores 87, DirectX 11 scores 37, DirectX 10 scores 32, and DirectX 12 scores 27. The Passmark G3D score is 5,983, while the G2D score is 899. The Passmark GPU Compute result measures 2,557.

The average benchmark score for the NVIDIA RTX A400 is 6,078, placing it at the 35th percentile among all GPUs in the database. The nearest rivals confirm a tight grouping. The NVIDIA GeForce MX230 posts an average score of 6,077 with a delta of 0 percent, making it statistically identical. The NVIDIA Quadro P2000 scores 6,049, which is 0.5 percent below the A400. The Intel Iris Pro Graphics 6200 scores 6,117, sitting 0.6 percent above the A400. The AMD Radeon 760M scores 6,019, which is 1 percent below. These deltas indicate that the RTX A400 sits near the center of a narrow performance band, with all four nearest rivals within roughly one percent of its average score.

The AMD Instinct MI455X has an avgBenchmarkScore of 0 and a percentileVsAllGpus of 50. Without recorded benchmark results, the database provides no measured performance data for this part. The percentile field of 50 is stored in the database, but with no benchmark scores behind it, this value cannot be interpreted as a tested performance ranking. The wins counters for both items are 0, confirming that no head-to-head test results exist.

The Verdict

The data supports a clear division. The AMD Instinct MI455X is specified as a 2 nm accelerator with 320,000 million transistors on a 2990 mm² die, using CDNA 5.0 architecture and HBM4 memory totaling 432 GB across a 24,576-bit bus. Its FP32 throughput is recorded at 157.3 TFLOPS, with FP16 also at 157.3 TFLOPS at a 1:1 ratio. The texture rate is 2,457.6 GTexel/s, and the pixel rate is listed as 0 MPixel/s with 0 ROPs. The power envelope is 2,300 W, with a suggested PSU of 2,700 W and no power connectors. It has no display outputs, no API support listed, and no measured benchmarks.

The NVIDIA RTX A400 is an 8 nm Ampere workstation card with 8,700 million transistors on a 200 mm² die. It has 4 GB of GDDR6 memory on a 64-bit bus with 96.00 GB/s of bandwidth. Its FP32 throughput is 2.706 TFLOPS, its texture rate is 42.29 GTexel/s, and its pixel rate is 28.19 GPixel/s. It includes 6 RT cores and 24 tensor cores, supports DirectX 12 Ultimate, OpenGL 4.6, and Vulkan 1.4, and draws 50 W with a suggested 250 W PSU. It has four mini-DisplayPort 1.4a outputs and an active production status.

The data indicates these products occupy entirely different segments. The MI455X is a compute-oriented module with no display path and no graphics API support, aimed at workloads that use its 432 GB HBM4 pool and 157.3 TFLOPS of FP32. The RTX A400 is a single-slot workstation card with display outputs, graphics API support, and a 50 W envelope, suited to tasks that require driver-level graphics compatibility and low power draw.

The benchmark results for the RTX A400 place it at the 35th percentile, with nearest rivals within one percent. The MI455X has no benchmark results, so no percentile comparison can be made. The recorded data shows a 58x difference in FP32 throughput (157.3 TFLOPS versus 2.706 TFLOPS), a 240x difference in memory capacity (432 GB versus 4 GB), and a 46x difference in TDP (2,300 W versus 50 W). These are specification-level differences, not measured performance deltas, because no shared benchmark exists.

FAQ

Q: What is the average benchmark score of the NVIDIA RTX A400?

A: The average benchmark score is 6,078, placing it at the 35th percentile among all GPUs in the database.

Q: Does the AMD Instinct MI455X have any recorded benchmark scores?

A: No. The database lists no benchmarks for the MI455X, and its average benchmark score is 0. Its percentile field is set to 50, but no test scores support that value.

Q: How does the RTX A400 compare to its nearest rivals?

A: The NVIDIA GeForce MX230 scores 6,077 with a 0 percent delta, the NVIDIA Quadro P2000 scores 6,049 with a 0.5 percent delta, the Intel Iris Pro Graphics 6200 scores 6,117 with a negative 0.6 percent delta, and the AMD Radeon 760M scores 6,019 with a 1 percent delta.

Q: Which GPU has higher FP32 throughput?

A: The AMD Instinct MI455X is rated at 157.3 TFLOPS FP32, while the NVIDIA RTX A400 is rated at 2.706 TFLOPS FP32.

Q: What display outputs does each card have?

A: The NVIDIA RTX A400 has 4x mini-DisplayPort 1.4a outputs. The AMD Instinct MI455X has no display outputs.

Q: What is the memory configuration of each card?

A: The AMD Instinct MI455X uses 432 GB of HBM4 on a 24,576-bit bus with 23.3 TB/s bandwidth. The NVIDIA RTX A400 uses 4 GB of GDDR6 on a 64-bit bus with 96.00 GB/s bandwidth.

Specification Differences

The two products differ in every recorded specification category. The AMD Instinct MI455X uses a 2 nm process from TSMC, while the NVIDIA RTX A400 uses an 8 nm process from Samsung. Transistor count differs substantially: the MI455X has 320,000 million transistors on a 2990 mm² die, giving a density of 107.0M per mm². The RTX A400 has 8,700 million transistors on a 200 mm² die, giving a density of 43.5M per mm².

Clock speeds differ in both direction and magnitude. The MI455X has a base clock of 1000 MHz and a boost clock of 2400 MHz, with memory at 1900 MHz (7.6 Gbps effective). The RTX A400 has a base clock of 1417 MHz and a boost clock of 1762 MHz, with memory at 1500 MHz (12 Gbps effective).

Memory specifications diverge completely. The MI455X has 432 GB of HBM4, a 24,576-bit bus, and 23.3 TB/s bandwidth. The RTX A400 has 4 GB of GDDR6, a 64-bit bus, and 96.00 GB/s bandwidth.

The compute unit counts differ by large factors. The MI455X has 32,768 shading units, 1,024 TMUs, and 0 ROPs. The RTX A400 has 768 shading units, 24 TMUs, and 16 ROPs. Pixel rate for the MI455X is 0 MPixel/s, while the RTX A400 produces 28.19 GPixel/s. Texture rate is 2,457.6 GTexel/s for the MI455X versus 42.29 GTexel/s for the RTX A400.

Power requirements diverge sharply. The MI455X has a TDP of 2,300 W and a suggested PSU of 2,700 W. The RTX A400 has a TDP of 50 W and a suggested PSU of 250 W. Neither card uses power connectors. The MI455X is an EAM Module, while the RTX A400 is single-slot. The bus interface differs: PCIe 6.0 x16 for the MI455X, PCIe 4.0 x8 for the RTX A400.

The RTX A400 has a physical footprint of 163 mm length and 69 mm height. The MI455X has no recorded dimensions. The RTX A400 has 4x mini-DisplayPort 1.4a outputs; the MI455X has none. The RTX A400 lists DirectX 12 Ultimate, OpenGL 4.6, and Vulkan 1.4 support. The MI455X lists N/A for all three APIs.

Release dates differ. The MI455X is dated 2026-07-22, while the RTX A400 is dated 2024-04-15. The RTX A400 has an active production status; the MI455X has no status recorded. The RTX A400 lists its predecessor as Quadro Turing and its successor as Workstation Ada. The MI455X lists its predecessor as Radeon Instinct with no successor recorded.

Architecture Differences

The AMD Instinct MI455X is built on CDNA 5.0 architecture, using the MI450 256CU chip, and belongs to the Instinct (MIx) generation. Its process node is 2 nm at TSMC, and it packs 320,000 million transistors into a 2990 mm² die. The architecture is designed around 256 compute units, yielding 32,768 shading units and 1,024 texture mapping units. It has no ROPs, no RT cores, and no tensor cores recorded. The memory subsystem uses HBM4 on a 24,576-bit interface, and the card implements PCIe 6.0 x16 connectivity. The MI455X has no display outputs and no graphics API support listed, consistent with an accelerator-oriented design. Its power delivery is unusual: no power connectors are listed despite a 2,300 W TDP and a 2,700 W suggested PSU, which aligns with the EAM Module form factor.

The NVIDIA RTX A400 is built on Ampere architecture, using the GA107 chip, and belongs to the Workstation Ampere (Ax000) generation. Its process node is 8 nm at Samsung, with 8,700 million transistors on a 200 mm² die. The GA107 configuration includes 768 shading units, 24 TMUs, 16 ROPs, 6 RT cores, and 24 tensor cores. The memory subsystem uses GDDR6 on a 64-bit bus. The A400 supports DirectX 12 Ultimate (12_2), OpenGL 4.6, and Vulkan 1.4, and it carries four mini-DisplayPort 1.4a outputs. Its production status is Active, and it uses PCIe 4.0 x8 connectivity.

The architectural gap is fundamental. The MI455X uses a newer 2 nm process, a transistor count over 36 times larger, and a die area nearly 15 times larger. The A400 uses an older 8 nm process with far fewer transistors. The MI455X has no graphics pipeline elements (0 ROPs, no RT cores, no tensor cores, no API support), while the A400 includes RT cores, tensor cores, and a full graphics API stack. The MI455X is built for raw compute throughput with massive memory bandwidth; the A400 is built for workstation graphics with moderate compute capability. The 157.3 TFLOPS FP32 figure for the MI455X is recorded as identical to its FP16 figure at a 1:1 ratio, indicating no FP16 acceleration over FP32. The A400 also shows a 1:1 ratio, with both FP32 and FP16 at 2.706 TFLOPS.