AMD Instinct MI300 vs NVIDIA RTX A400 Comparison

The Verdict

The AMD Instinct MI300 and NVIDIA RTX A400 occupy completely different segments of the GPU market, and the data reflects this divide. The MI300 is a compute-oriented accelerator with no display outputs, designed for high-throughput workloads, while the RTX A400 is a workstation card with full display capabilities and API support. The MI300 delivers substantially higher raw compute performance, but the RTX A400 is the only one of the two that can function as a traditional graphics card. For users requiring massive memory capacity and bandwidth, the MI300 is the clear choice. For those needing a compact, low-power workstation GPU with display outputs and broad API compatibility, the RTX A400 is the appropriate pick.

Where Each One Wins

The AMD Instinct MI300 wins decisively in raw compute throughput. Its FP32 rating reaches 47.87 TFLOPS, compared to 2.706 TFLOPS for the RTX A400. The MI300 also offers 128 GB of HBM3 memory with 5.32 TB/s bandwidth, while the RTX A400 provides 4 GB of GDDR6 with 96.00 GB/s. The MI300's texture rate of 1,496.0 GTexel/s dwarfs the RTX A400's 42.29 GTexel/s. The MI300 uses a 5 nm process from TSMC with 153,000 million transistors on a 1017 mm² die.

The NVIDIA RTX A400 wins in areas the MI300 cannot compete: it has display outputs (4x mini-DisplayPort 1.4a), supports DirectX 12 Ultimate (12_2), OpenGL 4.6, and Vulkan 1.4, while the MI300 reports N/A for all three APIs. The RTX A400 includes 6 RT cores and 24 tensor cores, features absent from the MI300's specification sheet. The RTX A400 also draws far less power at 50 W versus 600 W, and it requires no external power connectors, while the MI300 needs 2x 8-pin connectors.

Architecture Differences

The MI300 uses the CDNA 3.0 architecture on TSMC's 5 nm node, with the Aqua Vanjaram chip. The RTX A400 uses the Ampere architecture on Samsung's 8 nm node, with the GA107 chip. Transistor counts differ enormously: 153,000 million for the MI300 versus 8,700 million for the RTX A400. Die size also diverges sharply, with the MI300 measuring 1017 mm² against the RTX A400's 200 mm². Transistor density reflects the process gap: 150.4M per mm² for the MI300 versus 43.5M per mm² for the RTX A400.

Memory architecture separates the two completely. The MI300 uses 128 GB of HBM3 across an 8192-bit bus, delivering 5.32 TB/s. The RTX A400 uses 4 GB of GDDR6 across a 64-bit bus, delivering 96.00 GB/s. Shader configurations differ by an order of magnitude: 14,080 shading units, 880 TMUs, and 0 ROPs for the MI300, versus 768 shading units, 24 TMUs, and 16 ROPs for the RTX A400. The MI300 has no RT cores or tensor cores listed, while the RTX A400 includes 6 RT cores and 24 tensor cores.

Clock behavior also differs. The MI300 runs at a 1000 MHz base and 1700 MHz boost, with memory at 1300 MHz (5.2 Gbps effective). The RTX A400 runs at 1417 MHz base and 1762 MHz boost, with memory at 1500 MHz (12 Gbps effective). The MI300's pixel rate is listed as 0 MPixel/s, while the RTX A400 achieves 28.19 GPixel/s. The MI300 uses PCIe 5.0 x16, while the RTX A400 uses PCIe 4.0 x8.

FAQ

Q: Which GPU has higher FP32 compute performance?

A: The AMD Instinct MI300 delivers 47.87 TFLOPS, compared to 2.706 TFLOPS for the NVIDIA RTX A400.

Q: Do both cards support display outputs?

A: No. The RTX A400 has 4x mini-DisplayPort 1.4a outputs, while the MI300 has no display outputs.

Q: How do their memory capacities compare?

A: The MI300 offers 128 GB of HBM3, while the RTX A400 provides 4 GB of GDDR6.

Q: Which card supports DirectX?

A: Only the RTX A400 supports DirectX 12 Ultimate (12_2). The MI300 lists DirectX as N/A.

Q: What are the power requirements for each card?

A: The MI300 has a 600 W TDP and needs 2x 8-pin power connectors with a suggested 1000 W PSU. The RTX A400 has a 50 W TDP, requires no power connectors, and suggests a 250 W PSU.

Q: Which card has a smaller physical footprint?

A: The RTX A400 measures 163 mm in length and 69 mm in height, compared to 267 mm and 111 mm for the MI300. The RTX A400 is single-slot, while the MI300's slot width is not specified.

Head-to-Head Benchmarks

The RTX A400 has recorded benchmark scores, while the MI300 has none in the database. The RTX A400 achieves 22,844 in Geekbench OpenCL and 22,237 in Geekbench Vulkan. In Passmark tests, it scores 32 in DirectX 10, 37 in DirectX 11, 27 in DirectX 12, and 87 in DirectX 9. Its Passmark G2D score is 899, G3D score is 5,983, and GPU compute score is 2,557. The average benchmark score for the RTX A400 is 6,078, placing it in the 35th percentile of all GPUs.

The nearest rivals for the RTX A400 show tight competition. The NVIDIA GeForce MX230 averages 6,077, a 0% delta. The Intel Iris Pro Graphics 6200 averages 6,117, which is 0.6% higher. The NVIDIA Quadro P2000 averages 6,049, 0.5% lower. The AMD Radeon 760M averages 6,019, 1% lower. These deltas indicate the RTX A400 sits in a narrow performance band among its closest competitors.

The MI300 holds the 50th percentile among all GPUs with an average benchmark score of 0, and it has no nearest rivals listed. The absence of benchmark data for the MI300 means its measured performance cannot be directly compared to the RTX A400's recorded scores. The specification sheet, however, shows overwhelming advantages in compute, memory, and bandwidth for the MI300.

The MI300's FP32 rating of 47.87 TFLOPS is roughly 17.7 times the RTX A400's 2.706 TFLOPS. Its memory bandwidth of 5.32 TB/s is about 55 times the RTX A400's 96.00 GB/s. Texture rate stands at 1,496.0 GTexel/s versus 42.29 GTexel/s, a factor of roughly 35. These ratios come directly from the recorded specifications.

The RTX A400's pixel rate of 28.19 GPixel/s contrasts with the MI300's 0 MPixel/s, reflecting their different design purposes. The MI300 lacks ROPs entirely, while the RTX A400 has 16. The MI300's 14,080 shading units and 880 TMUs vastly outnumber the RTX A400's 768 shading units and 24 TMUs.

Specification Differences

The two cards differ across nearly every recorded field. The MI300 uses a 5 nm TSMC process, while the RTX A400 uses an 8 nm Samsung process. Transistors stand at 153,000 million for the MI300 versus 8,700 million for the RTX A400. Die size is 1017 mm² against 200 mm². Transistor density is 150.4M per mm² versus 43.5M per mm².

Base clocks differ: 1000 MHz for the MI300, 1417 MHz for the RTX A400. Boost clocks are closer: 1700 MHz versus 1762 MHz. Memory clocks are 1300 MHz (5.2 Gbps effective) for the MI300 and 1500 MHz (12 Gbps effective) for the RTX A400.

Memory size, type, bus width, and bandwidth all differ: 128 GB HBM3 with 8192-bit bus and 5.32 TB/s versus 4 GB GDDR6 with 64-bit bus and 96.00 GB/s. Shading units, TMUs, and ROPs differ as described above. RT cores and tensor cores exist only on the RTX A400 (6 and 24, respectively).

Pixel rate is 0 MPixel/s for the MI300 and 28.19 GPixel/s for the RTX A400. Texture rate is 1,496.0 GTexel/s versus 42.29 GTexel/s. FP32 and FP16 are both 47.87 TFLOPS (1:1) for the MI300, while the RTX A400 delivers 2.706 TFLOPS in both (1:1).

TDP is 600 W for the MI300 and 50 W for the RTX A400. Power connectors are 2x 8-pin for the MI300 and none for the RTX A400. Suggested PSU is 1000 W versus 250 W. The MI300 uses PCIe 5.0 x16, while the RTX A400 uses PCIe 4.0 x8. Display outputs are none for the MI300 and 4x mini-DisplayPort 1.4a for the RTX A400.

API support differs completely: the MI300 lists N/A for DirectX, OpenGL, and Vulkan, while the RTX A400 supports DirectX 12 Ultimate (12_2), OpenGL 4.6, and Vulkan 1.4. Dimensions differ: 267 mm by 111 mm for the MI300, 163 mm by 69 mm for the RTX A400. Slot width is single-slot for the RTX A400, unspecified for the MI300. Production status is active for the RTX A400, unspecified for the MI300. Release dates differ: the MI300 was released on 2023-01-03, the RTX A400 on 2024-04-15. The MI300's predecessor is Radeon Instinct, while the RTX A400's predecessor is Quadro Turing and its successor is Workstation Ada.