AMD Instinct MI350X vs AMD Instinct MI455X Comparison

Head-to-Head Benchmarks

The database contains no recorded benchmark scores for either the AMD Instinct MI350X or the AMD Instinct MI455X. Both entries show an average benchmark score of 0, and the head-to-head benchmark array is empty. Consequently, there are no direct performance measurements to compare, no wins recorded for either accelerator (winsA: 0, winsB: 0), and no nearest rival data is available for either product.

The absence of benchmark data means that any performance analysis must be derived entirely from the architectural specifications recorded in the database. The MI455X lists a FP32 throughput of 157.3 TFLOPS, which is more than double the MI350X's 72.09 TFLOPS. Similarly, FP16 performance follows the same ratio, with the MI455X delivering 157.3 TFLOPS against the MI350X's 72.09 TFLOPS (both at a 1:1 ratio). Texture fill rates show a smaller gap: the MI455X reaches 2,457.6 GTexel/s, while the MI350X manages 2,252.8 GTexel/s, a difference of approximately 9%.

Memory bandwidth shows a substantial divergence. The MI455X records 23.3 TB/s across a 24576-bit bus, while the MI350X provides 8.19 TB/s over an 8192-bit interface. The MI455X therefore offers roughly 2.84 times the memory bandwidth of the MI350X. Memory capacity also differs significantly, with the MI455X holding 432 GB compared to the MI350X's 288 GB.

Clock speeds are closer. Both accelerators share a 1000 MHz base clock, but the boost clock differs: the MI455X boosts to 2400 MHz, while the MI350X boosts to 2200 MHz. The memory clock, however, is slightly higher on the MI350X at 2000 MHz (8 Gbps effective) versus the MI455X's 1900 MHz (7.6 Gbps effective).

FAQ

Q: Which accelerator has a higher boost clock?

A: The AMD Instinct MI455X lists a boost clock of 2400 MHz, while the AMD Instinct MI350X lists 2200 MHz. Both have a base clock of 1000 MHz.

Q: How do the memory capacities compare?

A: The MI455X provides 432 GB of HBM4 memory, while the MI350X provides 288 GB of HBM3e memory. The MI455X offers 144 GB more capacity.

Q: What is the difference in FP32 compute performance?

A: The MI455X records 157.3 TFLOPS FP32, compared to the MI350X's 72.09 TFLOPS. The MI455X is approximately 2.18 times higher in raw FP32 throughput.

Q: Which product uses a newer fabrication process?

A: The MI455X uses a 2 nm process node, while the MI350X uses a 3 nm process node. Both are fabricated by TSMC.

Q: Are there any benchmark scores available for these accelerators?

A: No. The database shows an average benchmark score of 0 for both the MI350X and the MI455X, and the head-to-head benchmark array is empty. Neither product has recorded performance data.

Q: What are the transistor counts for each chip?

A: The MI455X contains 320,000 million transistors, while the MI350X contains 185,000 million transistors. The MI455X die size is 2990 mm², and the MI350X die size is 2380 mm².

Architecture Differences

The MI350X and MI455X belong to different CDNA generations. The MI350X is built on CDNA 4.0 architecture, while the MI455X uses CDNA 5.0. Both use a chip design designated as a 256CU configuration, but the underlying implementation differs substantially.

Fabrication nodes diverge: the MI350X is produced on a 3 nm process, and the MI455X on a 2 nm process, both at TSMC. Transistor counts reflect this: the MI455X packs 320,000 million transistors, versus 185,000 million for the MI350X. Transistor density also increases, with the MI455X at 107.0M per mm² and the MI350X at 77.7M per mm². Die size grows from 2380 mm² to 2990 mm².

Shader resources are doubled on the MI455X. The MI455X lists 32768 shading units, while the MI350X lists 16384. Texture mapping units remain equal at 1024 for both. Neither product has render output units (both show 0), and both show a pixel rate of 0 MPixel/s, consistent with compute-oriented accelerators that lack display outputs.

Memory architecture changes completely. The MI350X uses HBM3e with 288 GB capacity, an 8192-bit bus, and 8.19 TB/s bandwidth. The MI455X uses HBM4 with 432 GB capacity, a 24576-bit bus, and 23.3 TB/s bandwidth. The bus width triples, and bandwidth nearly triples.

Power specifications differ markedly. The MI350X has a TDP of 1000 W with a suggested PSU of 1400 W, while the MI455X has a TDP of 2300 W and a suggested PSU of 2700 W. Neither uses power connectors directly; both rely on module-level power delivery. The MI350X is an OAM Module with dimensions of 102 mm length and 165 mm width, while the MI455X is an EAM Module with no dimensions recorded.

Bus interfaces also change: the MI350X uses PCIe 5.0 x16, and the MI455X uses PCIe 6.0 x16. Both have no display outputs and no API support (DirectX, OpenGL, and Vulkan are all listed as N/A).

Release dates are recorded as 2025-06-11 for the MI350X and 2026-07-22 for the MI455X. Both share the same generation label, "Instinct (MIx)", and the same predecessor, "Radeon Instinct".

The Verdict

The recorded data indicates a clear generational shift. The MI455X outperforms the MI350X on every compute and memory metric where numbers exist: FP32, FP16, texture rate, memory bandwidth, memory capacity, shading units, and boost clock. The MI455X delivers 157.3 TFLOPS FP32 versus 72.09 TFLOPS, and 23.3 TB/s memory bandwidth versus 8.19 TB/s. These are not marginal improvements; the MI455X roughly doubles floating-point throughput and nearly triples memory bandwidth.

The MI350X holds only minor advantages. Its memory clock is slightly higher (2000 MHz versus 1900 MHz), and its physical dimensions are recorded (102 mm length, 165 mm width), whereas the MI455X has no dimensions listed. The MI350X also has a lower TDP at 1000 W versus 2300 W, which implies a less demanding power envelope, though the database does not provide efficiency metrics.

For users selecting between these two, the choice hinges on the workload requirements. The MI455X is the higher-capability accelerator across the board: more compute, more memory, more bandwidth, and a newer process node. The MI350X offers a smaller physical footprint and a substantially lower power draw, which may matter in constrained deployments. Neither product has benchmark scores, so real-world performance cannot be verified from the database; the analysis rests solely on specifications.

Specification Differences

| Specification | AMD Instinct MI350X | AMD Instinct MI455X |

|---|---|---|

| Architecture | CDNA 4.0 | CDNA 5.0 |

| Process Node | 3 nm | 2 nm |

| Foundry | TSMC | TSMC |

| Transistors | 185,000 million | 320,000 million |

| Die Size | 2380 mm² | 2990 mm² |

| Transistor Density | 77.7M / mm² | 107.0M / mm² |

| Base Clock | 1000 MHz | 1000 MHz |

| Boost Clock | 2200 MHz | 2400 MHz |

| Memory Clock | 2000 MHz (8 Gbps effective) | 1900 MHz (7.6 Gbps effective) |

| Memory Size | 288 GB | 432 GB |

| Memory Type | HBM3e | HBM4 |

| Memory Bus Width | 8192 bit | 24576 bit |

| Memory Bandwidth | 8.19 TB/s | 23.3 TB/s |

| Shading Units | 16384 | 32768 |

| TMUs | 1024 | 1024 |

| Pixel Rate | 0 MPixel/s | 0 MPixel/s |

| Texture Rate | 2,252.8 GTexel/s | 2,457.6 GTexel/s |

| FP32 | 72.09 TFLOPS | 157.3 TFLOPS |

| FP16 | 72.09 TFLOPS (1:1) | 157.3 TFLOPS (1:1) |

| TDP | 1000 W | 2300 W |

| Slot Width | OAM Module | EAM Module |

| Suggested PSU | 1400 W | 2700 W |

| Bus Interface | PCIe 5.0 x16 | PCIe 6.0 x16 |

| Display Outputs | No outputs | No outputs |

| DirectX | N/A | N/A |

| OpenGL | N/A | N/A |

| Vulkan | N/A | N/A |

| Dimensions | 102 mm length, 165 mm width | Not recorded |

| Release Date | 2025-06-11 | 2026-07-22 |

Where Each One Wins

The MI455X wins on all compute metrics. Its FP32 and FP16 throughput of 157.3 TFLOPS doubles the MI350X's 72.09 TFLOPS. Texture rate is higher at 2,457.6 GTexel/s versus 2,252.8 GTexel/s. Shading unit count is double at 32768 versus 16384. Memory bandwidth is 23.3 TB/s versus 8.19 TB/s, and capacity is 432 GB versus 288 GB. The MI455X also uses a smaller 2 nm process node and a newer PCIe 6.0 x16 interface.

The MI350X wins on power economy and physical size. Its TDP of 1000 W is less than half of the MI455X's 2300 W, and the suggested PSU requirement is 1400 W versus 2700 W. The MI350X is an OAM Module with recorded dimensions of 102 mm length and 165 mm width; the MI455X is an EAM Module with no dimensions available. The MI350X also has a higher memory clock at 2000 MHz versus 1900 MHz, though the effective bandwidth advantage belongs to the MI455X due to the wider bus.

For workloads that rely on raw compute and memory bandwidth, such as large-scale matrix operations or high-throughput inference, the MI455X is the stronger candidate based on specifications. For deployments where power draw and physical footprint are primary constraints, the MI350X presents a lighter-load option. Benchmark results are absent for both, so these conclusions derive strictly from the recorded architectural data.