AMD Instinct MI355X vs NVIDIA H20 Comparison

Where Each One Wins

The recorded database separates these two accelerators by workload character rather than by overall winner. The AMD Instinct MI355X dominates raw compute throughput metrics, while the NVIDIA H20 wins on efficiency-oriented specifications and a narrower power envelope.

The MI355X delivers 78.64 TFLOPS of FP32 compute, which is roughly double the H20's 39.54 TFLOPS. In FP16 workloads, the MI355X sustains 78.64 TFLOPS with a 1:1 ratio, while the H20 reaches 79.07 TFLOPS but does so through a 2:1 ratio, meaning its FP16 output is achieved by pairing two FP32 operations. The practical interpretation is that the MI355X holds a near-parity position in FP16 peak throughput, but its FP32 advantage is substantial.

Texture throughput also favors the AMD part. The MI355X posts 2,457.6 GTexel/s versus the H20's 617.8 GTexel/s, a nearly 4x gap. This suggests the MI355X is better suited for workloads that stress texture sampling or similar parallel memory-access patterns.

The H20 counteracts with a significantly lower thermal design power of 500 W compared to the MI355X's 1400 W. The NVIDIA part also uses a smaller die (814 mm²) and fewer transistors (80,000 million versus 185,000 million), which aligns with its more modest power draw. The H20's 24 ROPs deliver 47.52 GPixel/s, while the MI355X reports 0 MPixel/s, indicating the AMD part lacks traditional rasterization output stages entirely.

Memory capacity strongly favors the MI355X. It carries 288 GB of HBM3e across an 8192-bit bus, yielding 8.19 TB/s of bandwidth. The H20 offers 96 GB of HBM3 on a 6144-bit bus, reaching 4.03 TB/s. For large-model inference or training datasets that exceed 96 GB, the MI355X holds a clear capacity edge, while the H20's smaller footprint may suit inference workloads that fit within its memory.

The H20's pixel rate and ROP presence suggest it retains some graphics-related capability, though both parts have no display outputs and expose no DirectX, OpenGL, or Vulkan APIs. The database classifies both at the 50th percentile among all GPUs, with no benchmark scores or nearest rivals recorded, so the win split is based entirely on specification analysis.

Architecture Differences

The MI355X is built on CDNA 4.0 architecture using a 3 nm process at TSMC, while the H20 uses Hopper architecture on a 5 nm process, also at TSMC. The process node difference explains part of the transistor density gap: the H20 packs 98.3 million transistors per square millimeter versus the MI355X's 77.7 million per square millimeter. Despite the higher density, the H20's die is much smaller at 814 mm² compared to the MI355X's 2380 mm².

The MI355X uses the MI350 256CU chip, which contains 16,384 shading units and 1,024 texture mapping units. It has zero ROPs and no listed tensor cores or ray tracing cores. The H20 uses the GH100 chip with 9,984 shading units, 312 TMUs, 24 ROPs, and 312 tensor cores. The MI355X's lack of ROPs confirms its pure-compute orientation, whereas the H20 retains a minimal rasterization pipeline.

Memory architecture diverges significantly. The MI355X uses HBM3e with 8 Gbps effective speed, while the H20 uses HBM3 at 5.3 Gbps effective. The MI355X's 8192-bit bus width exceeds the H20's 6144-bit bus, contributing to its 8.19 TB/s bandwidth versus 4.03 TB/s.

Clock behavior differs as well. The H20 has a higher base clock of 1830 MHz and a boost clock of 1980 MHz. The MI355X starts at 1000 MHz base but boosts to 2400 MHz, a much wider boost range. The H20's memory clock runs at 1313 MHz, while the MI355X's memory clock is 2000 MHz.

The MI355X's power delivery relies on an OAM Module slot with no power connectors, and the system requires an 1800 W suggested PSU. The H20 uses an SXM Module form factor with a 900 W suggested PSU, and its production status is listed as Active, whereas the MI355X's production status is not recorded. The MI355X has no display outputs, matching the H20 in that regard, and both use PCIe 5.0 x16 interfaces.

The release dates differ by roughly 16 months. The H20 launched on 2024-01-31, while the MI355X arrived on 2025-06-11. The H20's predecessor is listed as Server Ada, and its successor is Server Blackwell. The MI355X's predecessor is Radeon Instinct, and no successor is recorded.

FAQ

Q: Which accelerator has higher FP32 compute throughput?

A: The AMD Instinct MI355X delivers 78.64 TFLOPS of FP32, more than double the NVIDIA H20's 39.54 TFLOPS.

Q: How do the two compare in memory capacity and bandwidth?

A: The MI355X offers 288 GB of HBM3e with 8.19 TB/s bandwidth, while the H20 provides 96 GB of HBM3 with 4.03 TB/s. The MI355X has both 3x the capacity and roughly 2x the bandwidth.

Q: What is the FP16 performance difference?

A: The MI355X reaches 78.64 TFLOPS with a 1:1 FP16 to FP32 ratio. The H20 reaches 79.07 TFLOPS but uses a 2:1 ratio, meaning its FP16 rate is derived from paired FP32 operations. The raw FP16 numbers are nearly identical, but the MI355X achieves this without the 2:1 scaling.

Q: Which part consumes less power?

A: The NVIDIA H20 has a TDP of 500 W, while the AMD Instinct MI355X has a TDP of 1400 W. The H20 also requires a 900 W suggested PSU versus the MI355X's 1800 W.

Q: Do either of these cards support graphics APIs?

A: Both report N/A for DirectX, OpenGL, and Vulkan, and both have no display outputs. They are compute-focused accelerators.

Q: What manufacturing processes are used?

A: The MI355X uses a 3 nm TSMC process, while the H20 uses a 5 nm TSMC process. The H20 has a higher transistor density at 98.3 million per mm² versus 77.7 million per mm².

Specification Differences

The two accelerators differ across nearly every measured specification. The MI355X uses a 3 nm process versus the H20's 5 nm. Transistor count is 185,000 million for the MI355X and 80,000 million for the H20. Die size spans 2380 mm² for the AMD part and 814 mm² for the NVIDIA part, while transistor density is 77.7 million per mm² versus 98.3 million per mm².

Clock speeds diverge with the MI355X base at 1000 MHz and boost at 2400 MHz, while the H20 bases at 1830 MHz and boosts to 1980 MHz. Memory clocks are 2000 MHz (8 Gbps effective) for the MI355X and 1313 MHz (5.3 Gbps effective) for the H20.

Memory configuration differs by capacity, type, bus width, and bandwidth. The MI355X uses 288 GB of HBM3e on an 8192-bit bus with 8.19 TB/s. The H20 uses 96 GB of HBM3 on a 6144-bit bus with 4.03 TB/s.

Shader resources vary considerably. The MI355X has 16,384 shading units and 1,024 TMUs, while the H20 has 9,984 shading units, 312 TMUs, and 24 ROPs. The MI355X reports zero ROPs and no tensor cores, while the H20 includes 312 tensor cores.

Pixel and texture rates reflect the ROP difference. The MI355X posts 0 MPixel/s and 2,457.6 GTexel/s, while the H20 posts 47.52 GPixel/s and 617.8 GTexel/s. FP32 output is 78.64 TFLOPS for the MI355X and 39.54 TFLOPS for the H20. FP16 output is 78.64 TFLOPS at a 1:1 ratio for the MI355X and 79.07 TFLOPS at a 2:1 ratio for the H20.

Power and form factor differ. The MI355X has a 1400 W TDP, uses an OAM Module slot, has no power connectors, and requires an 1800 W PSU. The H20 has a 500 W TDP, uses an SXM Module, and requires a 900 W PSU. Dimensions are recorded only for the MI355X: 102 mm length and 165 mm width. The H20 has no recorded dimensions.

Release timing and production status differ. The MI355X launched on 2025-06-11 with no production status listed. The H20 launched on 2024-01-31 and is listed as Active. The MI355X's predecessor is Radeon Instinct; the H20's predecessor is Server Ada and its successor is Server Blackwell.

Head-to-Head Benchmarks

The database records no direct head-to-head benchmark scores for these two parts, and neither has individual benchmark entries or nearest rivals. The comparison therefore rests on the recorded specification data, which reveals several decisive margins.

FP32 compute is the largest single gap. The MI355X's 78.64 TFLOPS is 39.10 TFLOPS higher than the H20's 39.54 TFLOPS, making the AMD part 99% faster in this metric. This is the clearest win for the MI355X and indicates a substantial advantage for workloads that rely on single-precision arithmetic.

Texture rate favors the MI355X at 2,457.6 GTexel/s versus 617.8 GTexel/s, a 1,839.8 GTexel/s difference. The AMD part is roughly 4x faster in this metric, which reflects its 1,024 TMUs against the H20's 312. Memory bandwidth follows a similar pattern: 8.19 TB/s versus 4.03 TB/s, a 4.16 TB/s gap that doubles the H20's bandwidth capability.

Memory capacity favors the MI355X by 192 GB, offering 288 GB against the H20's 96 GB. This difference determines whether a model or dataset fits on a single accelerator without sharding across multiple devices.

The H20's wins come in efficiency and power. Its 500 W TDP is 900 W lower than the MI355X's 1400 W, and its 900 W suggested PSU is half the MI355X's 1800 W requirement. The H20 also posts a higher base clock (1830 MHz versus 1000 MHz) and a higher transistor density (98.3 million per mm² versus 77.7 million per mm²).

FP16 peak is effectively a tie in raw numbers: 78.64 TFLOPS for the MI355X and 79.07 TFLOPS for the H20, a 0.43 TFLOPS difference. The ratio distinction matters, since the MI355X reaches its FP16 figure at a 1:1 ratio while the H20 uses a 2:1 ratio, but the recorded peak values are nearly identical.

Pixel rate is the only metric where the H20 has a non-zero value and the MI355X has zero. The H20 delivers 47.52 GPixel/s from its 24 ROPs, while the MI355X reports 0 MPixel/s, confirming that the AMD part has no rasterization pipeline. Both parts have no display outputs and no graphics API support, so this difference does not affect compute-centric deployments.

The overall picture from the data is a tradeoff between raw compute and memory capacity on the MI355X side versus power efficiency and a smaller physical footprint on the H20 side. The MI355X is the stronger choice for FP32-heavy workloads, large memory footprints, and bandwidth-bound tasks. The H20 is the more restrained option for power-constrained environments where its lower TDP and smaller die size are advantageous.