AMD Instinct MI455X vs NVIDIA GeForce RTX 4080 Max-Q Comparison

Head-to-Head Benchmarks

The recorded database contains no direct head-to-head benchmark entries for the AMD Instinct MI455X and the NVIDIA GeForce RTX 4080 Max-Q. Both products hold a percentile ranking of 50 against all GPUs, and their average benchmark scores are recorded as zero. This absence of measured data means the comparison must rely entirely on architectural specifications and calculated performance ceilings rather than observed application results.

The MI455X delivers a theoretical FP32 output of 157.3 TFLOPS, while the RTX 4080 Max-Q peaks at 20.04 TFLOPS. That is a 7.85x gap in raw floating-point throughput. Texture fill rate tells a similar story: the MI455X reaches 2,457.6 GTexel/s versus 313.2 GTexel/s for the NVIDIA part, a difference of roughly 7.8x. Pixel throughput, however, flips the narrative. The MI455X records 0 MPixel/s because its design omits conventional raster output units, while the RTX 4080 Max-Q manages 108.0 GPixel/s. The AMD accelerator is not built for pixel generation, so any comparison of rendering performance is meaningless without benchmark data to show how each handles real workloads.

Memory bandwidth also separates the two decisively. The MI455X offers 23.3 TB/s across a 24,576-bit HBM4 interface, compared to 432.0 GB/s on a 192-bit GDDR6 bus. The AMD part moves approximately 54 times more data per second. Capacity follows the same pattern: 432 GB versus 12 GB. Yet the RTX 4080 Max-Q includes 58 ray tracing cores and 232 tensor cores, features entirely absent from the MI455X specification sheet. The database lists no RT or tensor core counts for the AMD accelerator, which strongly suggests those units are not part of its architecture.

Architecture Differences

The two chips come from fundamentally different design philosophies. The MI455X uses the CDNA 5.0 architecture on TSMC's 2 nm process, built around the MI450 256CU die. The RTX 4080 Max-Q uses Ada Lovelace on TSMC's 5 nm node with the AD104 chip. Transistor counts reflect the scale difference: 320,000 million transistors on the MI455X against 35,800 million on the RTX 4080 Max-Q. Die size follows, with the AMD part measuring 2,990 mm² versus 294 mm². Interestingly, transistor density slightly favors NVIDIA at 121.8M per mm², compared to AMD's 107.0M per mm², indicating the smaller chip packs its transistors more tightly despite the node advantage of the larger one.

Clock speeds show a different trade-off. The MI455X runs a 1,000 MHz base and 2,400 MHz boost, while the RTX 4080 Max-Q operates at 795 MHz base and 1,350 MHz boost. The AMD chip clocks substantially higher, though it also consumes far more power. The TDP figures are extreme: 2,300 W for the MI455X versus 60 W for the RTX 4080 Max-Q. That is a 38.3x difference in thermal design power. The suggested PSU for the AMD part is 2,700 W, while the NVIDIA component lists no suggested PSU at all, consistent with its mobile, integrated form factor.

Memory technologies diverge completely. HBM4 with a 24,576-bit bus on the MI455X targets bandwidth density for compute workloads, while GDDR6 on a 192-bit bus in the RTX 4080 Max-Q prioritizes cost and availability for consumer laptops. The effective memory clock also differs: 7.6 Gbps for the AMD part versus 18 Gbps for the NVIDIA part, though the far wider AMD bus overwhelms that clock disadvantage. The MI455X uses an EAM Module slot width and no power connectors, while the RTX 4080 Max-Q is an IGP with no power connectors and display outputs described as portable-device dependent.

API support separates them entirely. The MI455X lists DirectX, OpenGL, and Vulkan as N/A, confirming it is not a consumer graphics product. The RTX 4080 Max-Q supports DirectX 12 Ultimate (12_2), OpenGL 4.6, and Vulkan 1.4. The AMD accelerator has no display outputs, while the NVIDIA part relies on the host portable device for display connectivity. The MI455X uses PCIe 6.0 x16, whereas the RTX 4080 Max-Q uses PCIe 4.0 x16.

The Verdict

The data indicates two products aimed at opposite ends of the computing spectrum. The MI455X is a massive compute accelerator with 32,768 shading units, 1,024 texture mapping units, and zero ROPs. The RTX 4080 Max-Q is a mobile graphics processor with 7,424 shading units, 232 TMUs, and 80 ROPs. The AMD part has no ray tracing or tensor core counts listed, while the NVIDIA part includes both. The MI455X also has no production status recorded, while the RTX 4080 Max-Q is marked as Active.

For FP32 and FP16 compute, the MI455X leads by 7.85x. For texture-heavy workloads, it leads by a similar margin. For any rasterization or ray-traced rendering, the RTX 4080 Max-Q is the only one of the two with the hardware to attempt it. The MI455X cannot output pixels at all, and its API support is nonexistent for graphics standards. The release dates confirm the generational gap: the MI455X launched on 2026-07-22, while the RTX 4080 Max-Q launched on 2023-01-02. The predecessor relationships also differ, with the MI455X following the Radeon Instinct line and the RTX 4080 Max-Q succeeding the GeForce 30 Mobile series and preceding the GeForce 50 Mobile.

Specification Differences

| Field | AMD Instinct MI455X | NVIDIA GeForce RTX 4080 Max-Q |

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

| Architecture | CDNA 5.0 | Ada Lovelace |

| Process Node | 2 nm | 5 nm |

| Transistors | 320,000 million | 35,800 million |

| Die Size | 2990 mm² | 294 mm² |

| Transistor Density | 107.0M / mm² | 121.8M / mm² |

| Base Clock | 1000 MHz | 795 MHz |

| Boost Clock | 2400 MHz | 1350 MHz |

| Memory Size | 432 GB | 12 GB |

| Memory Type | HBM4 | GDDR6 |

| Memory Bus Width | 24576 bit | 192 bit |

| Memory Bandwidth | 23.3 TB/s | 432.0 GB/s |

| Memory Clock | 1900 MHz, 7.6 Gbps effective | 2250 MHz, 18 Gbps effective |

| Shading Units | 32768 | 7424 |

| TMUs | 1024 | 232 |

| ROPs | 0 | 80 |

| RT Cores | None listed | 58 |

| Tensor Cores | None listed | 232 |

| Pixel Rate | 0 MPixel/s | 108.0 GPixel/s |

| Texture Rate | 2,457.6 GTexel/s | 313.2 GTexel/s |

| FP32 | 157.3 TFLOPS | 20.04 TFLOPS |

| FP16 | 157.3 TFLOPS (1:1) | 20.04 TFLOPS (1:1) |

| TDP | 2300 W | 60 W |

| Slot Width | EAM Module | IGP |

| Power Connectors | None | None |

| Suggested PSU | 2700 W | None listed |

| 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 |

| Production Status | None listed | Active |

| Release Date | 2026-07-22 | 2023-01-02 |

| Predecessor | Radeon Instinct | GeForce 30 Mobile |

| Successor | None listed | GeForce 50 Mobile |

FAQ

Q: Which GPU has higher FP32 compute performance?

A: The AMD Instinct MI455X delivers 157.3 TFLOPS, which is 7.85 times the 20.04 TFLOPS of the NVIDIA GeForce RTX 4080 Max-Q.

Q: Can the MI455X handle ray tracing?

A: The database lists no ray tracing core count for the MI455X, while the RTX 4080 Max-Q includes 58 RT cores. The MI455X also lists DirectX, OpenGL, and Vulkan as N/A, so ray-traced rendering is not part of its feature set.

Q: What is the memory capacity difference?

A: The MI455X has 432 GB of HBM4 memory, while the RTX 4080 Max-Q has 12 GB of GDDR6. The AMD part also offers 23.3 TB/s bandwidth against 432.0 GB/s for the NVIDIA part.

Q: Which product draws more power?

A: The MI455X has a TDP of 2,300 W and a suggested PSU of 2,700 W. The RTX 4080 Max-Q has a TDP of 60 W and no suggested PSU listed.

Q: Do both support modern graphics APIs?

A: No. The RTX 4080 Max-Q supports DirectX 12 Ultimate (12_2), OpenGL 4.6, and Vulkan 1.4. The MI455X lists all three APIs as N/A and has no display outputs.

Q: When were these products released?

A: The MI455X released on 2026-07-22, while the RTX 4080 Max-Q released on 2023-01-02.

Where Each One Wins

The MI455X wins decisively in compute throughput. Its 157.3 TFLOPS FP32 and FP16 performance, 2,457.6 GTexel/s texture rate, and 23.3 TB/s memory bandwidth position it for large-scale numerical workloads. The 432 GB HBM4 capacity supports datasets far beyond what a mobile GPU can address. The 32,768 shading units and 1,024 TMUs provide massive parallelism for shader-style compute. Its 2 nm process and 320,000 million transistors indicate a design built for density and scale, not efficiency in the traditional sense. The 2,400 MHz boost clock shows it can push frequency when power delivery allows, and the PCIe 6.0 x16 interface provides a modern, high-bandwidth host connection.

The RTX 4080 Max-Q wins in every area related to graphics output. Its 80 ROPs and 108.0 GPixel/s pixel rate enable actual display rendering, while its 58 RT cores and 232 tensor cores provide hardware acceleration for ray tracing and AI inference. The 12 GB GDDR6 memory, while small by comparison, is paired with a 192-bit bus that is entirely adequate for mobile gaming. Its 60 W TDP fits within laptop thermal envelopes, and its IGP slot width and portable-device-dependent display outputs confirm its intended placement in notebooks. The API support for DirectX 12 Ultimate, OpenGL 4.6, and Vulkan 1.4 means it can run standard graphics software, something the MI455X cannot attempt.

The data does not present a competition. It presents two tools for separate jobs. The MI455X is a compute accelerator without display output or graphics APIs, aimed at server-style installations. The RTX 4080 Max-Q is a mobile graphics processor with full rendering capabilities, aimed at laptops. The choice depends entirely on whether the workload involves pixel generation and graphics APIs or pure compute throughput on a massive scale.