AMD Instinct MI355X vs NVIDIA H20 NVL16 Comparison

The Verdict

The AMD Instinct MI355X and NVIDIA H20 NVL16 target entirely different segments of the accelerator market, and the recorded data makes that split unambiguous. The MI355X is the raw-throughput specialist: it carries 16,384 shading units, 1,024 texture mapping units, and delivers 78.64 TFLOPS of FP32 compute, which is nearly double the H20's 39.54 TFLOPS. It also holds a massive memory advantage with 288 GB of HBM3e on an 8192-bit bus, producing 8.19 TB/s of bandwidth versus the H20's 96 GB, 6144-bit HBM3 at 4.03 TB/s.

The NVIDIA H20 NVL16, by contrast, is the efficiency-optimized server part. Its 400 W TDP is less than one-third of the MI355X's 1400 W, and it is the only one of the two with an active production status. The H20 also brings 312 tensor cores, a feature the MI355X does not list at all. For FP16 workloads, the H20's 79.07 TFLOPS (2:1 ratio) actually exceeds the MI355X's 78.64 TFLOPS (1:1), meaning the NVIDIA part can match or beat the AMD card in mixed-precision neural network inference while drawing far less power.

The verdict from the data: the MI355X is the choice for memory-bound FP32 compute, massive model residency, and texture-heavy workloads. The H20 NVL16 is the choice for FP16 tensor-accelerated inference, power-constrained deployments, and any environment where the 400 W envelope and active production support matter more than raw FP32 throughput.

Architecture Differences

The two accelerators share a foundry, TSMC, but diverge on process node and every major architectural pillar. The MI355X is built on a 3 nm process and packs 185,000 million transistors into a 2380 mm² die, yielding a transistor density of 77.7M per mm². The H20 uses a 5 nm process with 80,000 million transistors on an 814 mm² die, achieving a higher density of 98.3M per mm² despite the older node. The MI355X's die is nearly three times larger in area and holds over twice the transistor count.

The chip-level designations tell the story: the MI355X uses the MI350 256CU chip under the CDNA 4.0 architecture, part of the Instinct (MIx) generation. The H20 uses the GH100 chip under the Hopper architecture, part of the Server Hopper (Hxx) generation. The MI355X's predecessor is Radeon Instinct, while the H20's predecessor is Server Ada and its successor is Server Blackwell. The H20 is still marked as Active in production, while the MI355X has no production status recorded.

Memory architecture differs fundamentally. The MI355X uses HBM3e with 288 GB capacity on an 8192-bit bus, clocked at 2000 MHz with 8 Gbps effective data rate, producing 8.19 TB/s. The H20 uses HBM3 with 96 GB on a 6144-bit bus, clocked at 1313 MHz with 5.3 Gbps effective, producing 4.03 TB/s. The MI355X has exactly three times the capacity and just over twice the bandwidth.

Compute resources also diverge sharply. The MI355X has 16,384 shading units and 1,024 TMUs, while the H20 has 9,984 shading units and 312 TMUs. The H20 lists 24 ROPs and 312 tensor cores; the MI355X lists zero ROPs and no tensor core count. The MI355X outputs 0 MPixel/s pixel rate but 2,457.6 GTexel/s texture rate, while the H20 outputs 47.52 GPixel/s and 617.8 GTexel/s. The MI355X's texture rate is 4 times higher, but the H20 has a meaningful pixel pipeline the AMD part lacks entirely.

Both use PCIe 5.0 x16 for host interface and have no display outputs. The MI355X is an OAM Module with 102 mm length and 165 mm width, while the H20 is an SXM Module with no dimensions recorded. The MI355X lists no power connectors and a suggested PSU of 1800 W; the H20 lists no power connector detail and a suggested PSU of 800 W.

Where Each One Wins

The MI355X wins decisively in FP32 raw compute. At 78.64 TFLOPS, it delivers 39.10 TFLOPS more than the H20's 39.54 TFLOPS, a 98.9% advantage. This makes it the clear choice for single-precision scientific simulation, dense linear algebra, and any FP32-heavy rendering or compute pipeline. Its texture rate of 2,457.6 GTexel/s versus 617.8 GTexel/s represents a 4x margin, so texture-bound workloads see an even larger relative gap.

The MI355X also wins on memory capacity and bandwidth. With 288 GB versus 96 GB, it can hold three times the model weights or dataset working set in on-package memory. Its 8.19 TB/s bandwidth is 2.03x the H20's 4.03 TB/s, which directly benefits memory-bound kernels, large-batch inference, and graph analytics that stream data through the memory subsystem.

The H20 NVL16 wins in FP16 throughput. Its 79.07 TFLOPS (2:1 ratio) edges past the MI355X's 78.64 TFLOPS (1:1) by 0.43 TFLOPS. This matters for transformer inference and training where FP16 is the dominant precision. The H20 also wins decisively on power efficiency: at 400 W versus 1400 W, it delivers comparable FP16 performance at 28.6% of the power draw. The H20's 312 tensor cores provide dedicated matrix math hardware, which the MI355X does not list at all.

The H20 wins on pixel rate as well. Its 47.52 GPixel/s is the only non-zero pixel output between the two, making it the only one capable of any rasterization work, albeit minimal given the server form factor. The H20's active production status and defined successor also indicate a clear product lifecycle, whereas the MI355X has no status recorded.

FAQ

Q: Which accelerator has higher FP32 compute throughput?

A: The AMD Instinct MI355X delivers 78.64 TFLOPS of FP32, which is 39.10 TFLOPS higher than the NVIDIA H20 NVL16's 39.54 TFLOPS.

Q: Which accelerator has more memory capacity?

A: The MI355X has 288 GB of HBM3e, exactly three times the H20's 96 GB of HBM3.

Q: Which accelerator has higher memory bandwidth?

A: The MI355X produces 8.19 TB/s over an 8192-bit bus, while the H20 produces 4.03 TB/s over a 6144-bit bus. The MI355X's bandwidth is roughly double.

Q: Which accelerator has higher FP16 throughput?

A: The NVIDIA H20 NVL16 delivers 79.07 TFLOPS of FP16 with a 2:1 ratio, narrowly exceeding the MI355X's 78.64 TFLOPS at 1:1.

Q: Which accelerator has a lower power draw?

A: The H20 NVL16 has a 400 W TDP with an 800 W suggested PSU, while the MI355X has a 1400 W TDP with an 1800 W suggested PSU.

Q: Which accelerator has tensor cores?

A: Only the H20 NVL16 lists tensor cores, with 312 units. The MI355X does not report any tensor core count.

Head-to-Head Benchmarks

The recorded data shows no direct head-to-head benchmark scores, so the comparison rests on the architectural specifications. The largest win for the MI355X is in FP32 compute: 78.64 TFLOPS against 39.54 TFLOPS, a 39.10 TFLOPS margin that means the AMD part completes FP32 work in roughly half the time of the NVIDIA part, all else equal. The texture rate gap is even wider in relative terms: 2,457.6 GTexel/s versus 617.8 GTexel/s, a 1,839.8 GTexel/s difference that gives the MI355X a 4x advantage in texture-bound operations.

The memory bandwidth differential is the second major MI355X win. At 8.19 TB/s versus 4.03 TB/s, the AMD part moves 4.16 TB/s more data per second. For workloads that stream large tensors or random-access large pools, this difference compounds across kernel execution time. The 288 GB versus 96 GB capacity split means the MI355X can hold 192 GB more in on-package memory, eliminating the need for host memory spills that the H20 must perform when working sets exceed 96 GB.

The H20's largest win is power efficiency. At 400 W versus 1400 W, the NVIDIA part draws 1,000 W less. For FP16 workloads, the H20 achieves 79.07 TFLOPS at 400 W, while the MI355X achieves 78.64 TFLOPS at 1400 W. The H20 produces 0.198 TFLOPS per watt in FP16 versus the MI355X's 0.056 TFLOPS per watt, a 3.5x efficiency advantage. This makes the H20 dramatically easier to cool, power, and densely populate in a server chassis.

The tensor core count is another H20 advantage. With 312 tensor cores versus none reported on the MI355X, the H20 has dedicated hardware for matrix multiplication and fused multiply-accumulate operations that dominate transformer architectures. The MI355X must rely on its general-purpose shading units for these workloads, which explains why the H20's FP16 output with a 2:1 ratio can match the MI355X's 1:1 ratio despite far fewer shading units.

The H20 also holds the pixel rate distinction. Its 47.52 GPixel/s is the only pixel output available, while the MI355X records 0 MPixel/s. Neither part has display outputs, so this difference is largely theoretical for server deployments, but it confirms the H20 retains a rasterization path the MI355X lacks entirely.

Transistor density favors the H20 as well. At 98.3M transistors per mm², the H20 packs its 80,000 million transistors into 814 mm², while the MI355X spreads 185,000 million transistors across 2380 mm² at 77.7M per mm². The H20's higher density on a 5 nm node versus the MI355X's 3 nm node indicates different design priorities: the NVIDIA chip emphasizes compactness and power efficiency, while the AMD chip prioritizes raw scale and memory integration.

The release timeline shows the H20 arriving later, dated 2025-09-01, while the MI355X is dated 2025-06-11. The H20 has a defined successor in Server Blackwell, while the MI355X lists none. The H20's production status of Active further distinguishes it as a currently available product, whereas the MI355X's status is unrecorded. For deployment decisions, the H20 offers a clear lifecycle path, while the MI355X's roadmap remains unspecified in the database.