AMD Instinct MI455X vs NVIDIA H20 Comparison

Head-to-Head Benchmarks

The database does not contain any recorded benchmark scores for the AMD Instinct MI455X or the NVIDIA H20. Both entries show an average benchmark score of zero, and the head-to-head benchmark comparison list is empty. Consequently, there are no direct performance deltas, win counts, or percentile rankings to interpret between these two accelerators. The recorded data sets each device at the 50th percentile against all GPUs, but this figure is uniform and does not reflect any measured competition, as no benchmark submissions exist for either part.

Without benchmark results, the only quantitative comparisons available come from the specification sheet. The AMD Instinct MI455X lists a FP32 throughput of 157.3 TFLOPS and a FP16 throughput of 157.3 TFLOPS (1:1 ratio). The NVIDIA H20 lists a FP32 throughput of 39.54 TFLOPS and a FP16 throughput of 79.07 TFLOPS (2:1 ratio). These figures indicate the AMD part delivers approximately four times the FP32 arithmetic rate and roughly double the FP16 rate on paper, but these are theoretical peak rates, not measured application scores. The absence of actual benchmark data means no statement can be made about real-world workload performance, efficiency under load, or sustained clock behavior.

The texture rate also diverges sharply. The MI455X reports 2,457.6 GTexel/s, while the H20 reports 617.8 GTexel/s, a gap of roughly fourfold. The pixel rates are even more extreme: the MI455X lists 0 MPixel/s, whereas the H20 lists 47.52 GPixel/s. These differences stem from the architectural design of each chip, but without benchmarks, the impact on specific rendering or compute tasks remains unquantified in the database.

Where Each One Wins

Based solely on the specification data, the AMD Instinct MI455X holds clear advantages in raw compute throughput. Its FP32 figure of 157.3 TFLOPS is substantially higher than the H20’s 39.54 TFLOPS, suggesting a design oriented toward workloads that rely on single-precision floating-point math, such as certain scientific simulations or general compute kernels. Its FP16 rate of 157.3 TFLOPS also exceeds the H20’s 79.07 TFLOPS, though the H20’s 2:1 ratio indicates it processes two FP16 operations per FP32 operation, a common pattern for tensor-heavy tasks. The MI455X’s 1:1 ratio implies it does not differentiate between these precisions, which may simplify programming but does not offer the same specialized throughput boost for reduced-precision work.

The NVIDIA H20 wins on pixel processing capability, as it is the only one of the two with a non-zero pixel rate (47.52 GPixel/s). The MI455X reports 0 MPixel/s, meaning it has no raster output units engaged for pixel generation. This makes the H20 the only candidate for any workload that involves pixel output, though neither device has display outputs, so this is strictly a compute-oriented metric. The H20 also has a higher base clock (1830 MHz versus 1000 MHz) and a boost clock of 1980 MHz versus 2400 MHz, but the MI455X boosts higher overall. The H20’s tensor cores, which number 312, provide a dedicated path for matrix operations, whereas the MI455X does not list tensor cores in its specifications.

Memory capacity and bandwidth are decisively in the MI455X’s favor. It offers 432 GB of HBM4 across a 24576-bit bus, yielding 23.3 TB/s of bandwidth. The H20 offers 96 GB of HBM3 across a 6144-bit bus, yielding 4.03 TB/s. The MI455X provides over four times the capacity and nearly six times the bandwidth, which would benefit large model training or inference workloads that must keep substantial datasets resident on the accelerator. The H20’s smaller memory footprint may still suit smaller batch sizes or models that fit within 96 GB.

Architecture Differences

The two accelerators use fundamentally different chip designs. The AMD Instinct MI455X is built on the CDNA 5.0 architecture, which is a compute-optimized design derived from AMD’s Instinct product line. Its chip is labeled “MI450 256CU,” indicating 256 compute units. The NVIDIA H20 uses the Hopper architecture, which is NVIDIA’s dedicated data center compute design, with a chip labeled “GH100.” Hopper is a distinct generation from AMD’s CDNA, and the H20 belongs to NVIDIA’s Server Hopper (Hxx) family.

The manufacturing process differs significantly. The MI455X uses a 2 nm process node at TSMC, while the H20 uses a 5 nm process node, also at TSMC. This process gap contributes to a large difference in transistor count: the MI455X integrates 320,000 million transistors, whereas the H20 integrates 80,000 million. The die sizes reflect this disparity: the MI455X has a die size of 2990 mm², while the H20 is 814 mm². Transistor density is comparable, with the MI455X at 107.0M per mm² and the H20 at 98.3M per mm², so the MI455X’s larger die is primarily a function of its much higher transistor budget.

The memory subsystems are also architecturally distinct. The MI455X uses HBM4 memory, the newest generation listed in the database, while the H20 uses HBM3. The bus widths are drastically different: 24576 bits for the MI455X versus 6144 bits for the H20. This explains the bandwidth gap, as wider buses allow more parallel memory accesses. The MI455X’s memory clock is 1900 MHz (7.6 Gbps effective), while the H20’s is 1313 MHz (5.3 Gbps effective). The MI455X also has no ROPs, meaning it does not rasterize pixels, while the H20 has 24 ROPs. Neither device has display outputs, and both list their APIs as N/A for DirectX, OpenGL, and Vulkan, confirming they are compute-only parts.

Specification Differences

The AMD Instinct MI455X and NVIDIA H20 differ across nearly every major specification field. The MI455X has a base clock of 1000 MHz and a boost clock of 2400 MHz. The H20 has a base clock of 1830 MHz and a boost clock of 1980 MHz. The MI455X’s boost clock is 420 MHz higher than the H20’s, but its base clock is 830 MHz lower.

Compute unit counts scale accordingly. The MI455X has 32,768 shading units, 1,024 texture mapping units, and no ROPs. The H20 has 9,984 shading units, 312 texture mapping units, and 24 ROPs. The MI455X also has no tensor cores listed, while the H20 has 312 tensor cores. The FP32 and FP16 rates are detailed earlier: 157.3 TFLOPS for both precisions on the MI455X, and 39.54 TFLOPS (FP32) with 79.07 TFLOPS (FP16) on the H20.

Memory configurations are starkly different. The MI455X ships with 432 GB of HBM4 memory, a 24576-bit bus, and 23.3 TB/s bandwidth. The H20 ships with 96 GB of HBM3 memory, a 6144-bit bus, and 4.03 TB/s bandwidth. Pixel rates are 0 MPixel/s for the MI455X and 47.52 GPixel/s for the H20. Texture rates are 2,457.6 GTexel/s for the MI455X and 617.8 GTexel/s for the H20.

Power and physical specifications also diverge. The MI455X has a TDP of 2300 W with a suggested PSU of 2700 W. The H20 has a TDP of 500 W with a suggested PSU of 900 W. The MI455X uses an EAM Module slot width, while the H20 uses an SXM Module slot width. The MI455X has no power connectors listed, and the H20 also has no power connector detail. The bus interface is PCIe 6.0 x16 for the MI455X and PCIe 5.0 x16 for the H20. Neither device has display outputs.

Release timing is another differentiator. The MI455X has a release date of 2026-07-22, while the H20 has a release date of 2024-01-31. The H20 is marked as Active in production status, with a predecessor of Server Ada and a successor of Server Blackwell. The MI455X has no production status listed, its predecessor is Radeon Instinct, and it has no successor listed. Neither device has a launch MSRP in the database.

FAQ

Q: Which accelerator has more memory?

A: The AMD Instinct MI455X has 432 GB of HBM4 memory, while the NVIDIA H20 has 96 GB of HBM3 memory, a difference of 336 GB.

Q: What is the FP32 throughput difference?

A: The MI455X lists 157.3 TFLOPS of FP32 performance, while the H20 lists 39.54 TFLOPS, making the AMD part approximately four times higher on this specification.

Q: Does the NVIDIA H20 have tensor cores?

A: Yes, the H20 lists 312 tensor cores. The AMD Instinct MI455X does not list any tensor cores in the database.

Q: What is the memory bandwidth of each device?

A: The MI455X delivers 23.3 TB/s of memory bandwidth, and the H20 delivers 4.03 TB/s.

Q: Which device has a higher boost clock?

A: The MI455X has a boost clock of 2400 MHz, while the H20 has a boost clock of 1980 MHz.

Q: Are there any benchmark scores recorded for either accelerator?

A: No, both entries have an average benchmark score of 0, and the head-to-head benchmark list is empty.

The Verdict

Based strictly on the recorded data, the AMD Instinct MI455X is the choice for workloads that demand maximum compute throughput and memory capacity. Its FP32 rate of 157.3 TFLOPS, FP16 rate of 157.3 TFLOPS, 432 GB of memory, and 23.3 TB/s bandwidth are all significantly higher than the corresponding figures for the NVIDIA H20. The MI455X also has a higher boost clock (2400 MHz versus 1980 MHz), more shading units (32,768 versus 9,984), and a newer process node (2 nm versus 5 nm). Its transistor count of 320,000 million dwarfs the H20’s 80,000 million, and its die size of 2990 mm² is much larger than the H20’s 814 mm². For any application that can use its raw arithmetic rates and large memory footprint, the MI455X is the stronger part on paper.

The NVIDIA H20 is the choice when power consumption and pixel processing matter. Its TDP of 500 W is far below the MI455X’s 2300 W, and its suggested PSU of 900 W is lower than the MI455X’s 2700 W. The H20 is also the only one of the two with a non-zero pixel rate (47.52 GPixel/s) and a defined tensor core count (312). Its FP16 performance of 79.07 TFLOPS, while lower than the MI455X’s 157.3 TFLOPS, comes from a 2:1 ratio that may indicate a more specialized path for reduced-precision operations. The H20’s smaller memory footprint (96 GB) and bandwidth (4.03 TB/s) are limiting, but its lower power envelope and active production status make it a more immediately deployable option in environments constrained by power delivery or thermal capacity.

The absence of benchmark scores means no empirical performance verdict can be rendered. The specification sheet favors the MI455X in almost every raw compute and memory metric, while the H20 offers advantages in pixel rate, tensor core availability, and power efficiency. Users with workloads that fit within the H20’s 96 GB memory and require its tensor cores may find it sufficient, but the MI455X’s specifications position it as the higher-capability device for large-scale compute tasks. Neither device has a launch MSRP recorded, so no cost-based comparison is possible from the database.