AMD Instinct MI455X vs AMD Radeon RX 7900M Comparison

Where Each One Wins

The recorded data presents a straightforward split: the AMD Radeon RX 7900M has measurable benchmark results, while the AMD Instinct MI455X has no recorded benchmark scores, an average score of 0, and a percentile rank of 50 among all GPUs. The RX 7900M, by contrast, holds a 94th percentile ranking and an average benchmark score of 97,487.

The RX 7900M's wins are concrete. In 3DMark Steel Nomad DX12, it scores 4,201. In Geekbench OpenCL, it reaches 129,499. In Geekbench Vulkan, it posts 158,760. These are the only benchmark entries in the database for either product, so all comparative analysis must draw from these figures. The MI455X has zero wins in any recorded test, and the head-to-head benchmark array is empty. The database lists winsA as 0 and winsB as 0, confirming no direct comparison tests exist.

Where each one wins is therefore defined by presence versus absence. The RX 7900M wins in every measurable category because it has data. The MI455X wins nowhere in terms of recorded performance tests, though its architecture and specifications suggest a different intended role, which the database does not quantify.

Architecture Differences

The two AMD parts diverge sharply at the architectural level. The Instinct MI455X uses the MI450 256CU chip built on CDNA 5.0 architecture, while the Radeon RX 7900M uses the Navi 31 chip with RDNA 3.0 architecture. The MI455X belongs to the Instinct (MIx) generation; the RX 7900M belongs to the Navi Mobile (RX 7000M) generation and carries the Plum Bonito codename.

Process nodes differ: the MI455X is fabricated on a 2 nm process at TSMC, whereas the RX 7900M uses a 5 nm process, also at TSMC. Transistor counts are far apart. The MI455X packs 320,000 million transistors on a 2990 mm² die, giving a density of 107.0M per mm². The RX 7900M has 57,700 million transistors on a 529 mm² die, with a density of 109.1M per mm². Although the transistor density is slightly higher on the RX 7900M, the absolute scale of the MI455X is enormous by comparison.

Memory architecture is fundamentally different. The MI455X uses 432 GB of HBM4 memory on a 24576-bit bus, delivering 23.3 TB/s of bandwidth. The RX 7900M uses 16 GB of GDDR6 memory on a 256-bit bus, with 576.0 GB/s of bandwidth. Clock speeds also differ: the MI455X runs at a 1000 MHz base and 2400 MHz boost, with memory at 1900 MHz (7.6 Gbps effective). The RX 7900M has a higher base of 1825 MHz and a lower boost of 2090 MHz, with memory at 2250 MHz (18 Gbps effective).

Compute resources diverge as well. The MI455X has 32,768 shading units, 1,024 TMUs, and 0 ROPs. The RX 7900M has 4,608 shading units, 288 TMUs, and 192 ROPs. The MI455X has no listed ray tracing cores or tensor cores; the RX 7900M has 72 ray tracing cores and no tensor cores. The MI455X posts a pixel rate of 0 MPixel/s and a texture rate of 2,457.6 GTexel/s. The RX 7900M posts 401.3 GPixel/s and 601.9 GTexel/s.

FP32 and FP16 throughput tell a similar story. The MI455X reaches 157.3 TFLOPS in both FP32 and FP16 at a 1:1 ratio. The RX 7900M reaches 38.52 TFLOPS in FP32 and 77.05 TFLOPS in FP16 at a 2:1 ratio. Thermal design power differs substantially: 2300 W for the MI455X versus 180 W for the RX 7900M.

Interface and output capabilities also differ. The MI455X uses PCIe 6.0 x16, has no display outputs, and is an EAM Module with no power connectors and a suggested PSU of 2700 W. The RX 7900M uses PCIe 4.0 x16, has portable device dependent display outputs, is an IGP, has no power connectors, and no suggested PSU is listed. API support is absent for the MI455X (DirectX N/A, OpenGL N/A, Vulkan N/A), while the RX 7900M supports DirectX 12 Ultimate (12_2), OpenGL 4.6, and Vulkan 1.4.

FAQ

Q: Which GPU has a higher benchmark score?

A: The AMD Radeon RX 7900M has recorded benchmark scores, with an average of 97,487 and a 94th percentile ranking. The AMD Instinct MI455X has no recorded benchmarks, an average score of 0, and a 50th percentile ranking.

Q: What is the memory capacity difference?

A: The Instinct MI455X uses 432 GB of HBM4 memory on a 24576-bit bus with 23.3 TB/s bandwidth. The Radeon RX 7900M uses 16 GB of GDDR6 memory on a 256-bit bus with 576.0 GB/s bandwidth.

Q: How do the architectures compare?

A: The MI455X uses CDNA 5.0 architecture with the MI450 256CU chip, while the RX 7900M uses RDNA 3.0 architecture with the Navi 31 chip. The MI455X is on a 2 nm process, and the RX 7900M is on a 5 nm process.

Q: What is the compute throughput difference?

A: The MI455X delivers 157.3 TFLOPS in FP32 and 157.3 TFLOPS in FP16 (1:1). The RX 7900M delivers 38.52 TFLOPS in FP32 and 77.05 TFLOPS in FP16 (2:1).

Q: Which GPU has ray tracing support?

A: The Radeon RX 7900M has 72 ray tracing cores. The Instinct MI455X has no listed ray tracing cores.

Q: What is the power requirement difference?

A: The MI455X has a TDP of 2300 W and a suggested PSU of 2700 W. The RX 7900M has a TDP of 180 W and no listed suggested PSU.

Specification Differences

The two GPUs differ across nearly every specification field in the database.

| Specification | AMD Instinct MI455X | AMD Radeon RX 7900M |

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

| Architecture | CDNA 5.0 | RDNA 3.0 |

| Process Node | 2 nm | 5 nm |

| Transistors | 320,000 million | 57,700 million |

| Die Size | 2990 mm² | 529 mm² |

| Transistor Density | 107.0M / mm² | 109.1M / mm² |

| Base Clock | 1000 MHz | 1825 MHz |

| Boost Clock | 2400 MHz | 2090 MHz |

| Memory Clock | 1900 MHz (7.6 Gbps effective) | 2250 MHz (18 Gbps effective) |

| Memory Size | 432 GB | 16 GB |

| Memory Type | HBM4 | GDDR6 |

| Memory Bus Width | 24576 bit | 256 bit |

| Memory Bandwidth | 23.3 TB/s | 576.0 GB/s |

| Shading Units | 32768 | 4608 |

| TMUs | 1024 | 288 |

| ROPs | 0 | 192 |

| RT Cores | None | 72 |

| Pixel Rate | 0 MPixel/s | 401.3 GPixel/s |

| Texture Rate | 2,457.6 GTexel/s | 601.9 GTexel/s |

| FP32 | 157.3 TFLOPS | 38.52 TFLOPS |

| FP16 | 157.3 TFLOPS (1:1) | 77.05 TFLOPS (2:1) |

| TDP | 2300 W | 180 W |

| Slot Width | EAM Module | IGP |

| Bus Interface | PCIe 6.0 x16 | PCIe 4.0 x16 |

| Display Outputs | No outputs | Portable Device Dependent |

| DirectX | N/A | 12 Ultimate (12_2) |

| OpenGL | N/A | 4.6 |

| Vulkan | N/A | 1.4 |

The release dates differ: the MI455X is dated 2026-07-22, and the RX 7900M is dated 2023-10-18. The RX 7900M has an active production status; the MI455X has none listed. The RX 7900M has a predecessor, Polaris Mobile; the MI455X lists Radeon Instinct as its predecessor.

Head-to-Head Benchmarks

No direct head-to-head benchmark results exist in the database. The headToHeadBenchmarks array is empty, and winsA and winsB are both 0. Therefore, any comparison must rely on the RX 7900M's standalone scores and the MI455X's absence of scores.

The RX 7900M's 3DMark Steel Nomad DX12 score of 4,201 stands alone. Its Geekbench OpenCL score of 129,499 and Geekbench Vulkan score of 158,760 are also standalone. These are the only recorded performance numbers in the database. The MI455X has none, so there are no winning margins to calculate in either direction.

The nearest rivals for the RX 7900M provide context. Its average score of 97,487 is 0.4% above the AMD Radeon Pro VII (97,131), 4.3% below the NVIDIA Quadro RTX 6000 (101,872), 5.4% above the AMD Radeon Instinct MI60 (92,466), and 6.3% above the NVIDIA RTX A4500 (91,671). These deltas show the RX 7900M sits in a competitive mid-range band relative to those professional cards, but no equivalent data exists for the MI455X.

The biggest wins in this comparison are structural. The RX 7900M wins on having any benchmark data at all, on API support, on ray tracing cores, on ROPs, and on pixel rate. The MI455X wins on memory capacity, memory bandwidth, shading units, texture rate, FP32 and FP16 throughput, and process node. Neither wins a direct test because no direct test was recorded.

The Verdict

The data indicates two very different products with no overlapping benchmark evidence. The AMD Radeon RX 7900M is a measured, active GPU with a 94th percentile ranking, an average benchmark score of 97,487, and three specific test results in 3DMark and Geekbench. It supports DirectX 12 Ultimate, OpenGL 4.6, and Vulkan 1.4, has 72 ray tracing cores, 192 ROPs, and a 401.3 GPixel/s pixel rate. Its 180 W TDP and 16 GB GDDR6 memory fit a mobile or integrated graphics context, given its IGP slot width and portable device dependent outputs.

The AMD Instinct MI455X is a different class of hardware. It carries 432 GB of HBM4 memory, 23.3 TB/s of bandwidth, 32,768 shading units, and 157.3 TFLOPS in both FP32 and FP16. Its 2300 W TDP and 2700 W suggested PSU indicate a high-power, compute-oriented module, consistent with its EAM Module form factor and lack of display outputs. Its CDNA 5.0 architecture and 2 nm process are the most advanced in this comparison, but no benchmark scores exist to validate performance in practice.

Who should pick which depends strictly on the recorded facts. A user needing verified, current performance data, ray tracing support, and a standard graphics API stack should select the RX 7900M, because it is the only one with measurable results. A user needing extreme memory capacity, massive compute throughput, and a newer process node, with no requirement for display outputs or graphics APIs, should consider the MI455X, but must accept that its performance is unmeasured in this database. The verdict is not about which is faster; it is about which has evidence, and only the RX 7900M does.