AMD Instinct MI455X vs NVIDIA L4 Comparison

Head-to-Head Benchmarks

The recorded data contains benchmark results for the NVIDIA L4, while the AMD Instinct MI455X has no benchmark entries in the database. This asymmetry makes a direct score-for-score comparison impossible. The L4 produces a Geekbench OpenCL score of 140,838 and a Geekbench Vulkan score of 121,306, giving an average benchmark score of 131,072. The MI455X carries an average benchmark score of 0 with zero recorded tests, which places it at the 50th percentile of all GPUs in the database. The L4, by contrast, sits at the 95th percentile.

Since the MI455X lacks benchmark scores, the nearest rival comparisons in the database are all tied to the L4. The L4 trails the NVIDIA GeForce RTX 3090 Ti by 0.7%, with the rival scoring 131,938 against the L4's 131,072 average. It also sits 3.1% behind the NVIDIA RTX 4000 Ada Generation, which scores 135,218, and 3.1% behind the NVIDIA A10M, which scores 135,230. The AMD Radeon PRO W6800 leads the L4 by 3.2% with a score of 135,396. These deltas indicate that the L4 operates in a competitive band near these workstation and datacenter cards, with the closest margin being the 0.7% gap to the GeForce RTX 3090 Ti.

The absence of MI455X benchmarks means the database cannot confirm whether its raw compute specifications translate into practical performance wins. The L4's OpenCL score surpasses its Vulkan score by roughly 16%, which suggests the card has a stronger showing in compute-oriented workloads than in graphics API tests. The MI455X's zero benchmark score and 50th percentile placement reflect a lack of measured data rather than an actual performance estimate, so any head-to-head comparison must rely on architectural specifications instead of empirical results.

Architecture Differences

The two accelerators diverge sharply at the architectural level. The AMD Instinct MI455X uses the CDNA 5.0 architecture, built on a TSMC 2 nm process node, while the NVIDIA L4 uses the Ada Lovelace architecture on a TSMC 5 nm node. The MI455X integrates 320,000 million transistors on a 2990 mm² die, yielding a transistor density of 107.0M per mm². The L4 packs 35,800 million transistors on a 294 mm² die, with a higher density of 121.8M per mm². Despite the MI455X's enormous transistor count, the L4 achieves greater packing density, which reflects the different design philosophies: the MI455X prioritizes raw scale, while the L4 focuses on efficiency within a smaller footprint.

The MI455X uses the MI450 256CU chip and belongs to the Instinct (MIx) generation, with a predecessor listed as Radeon Instinct. The L4 uses the AD104 chip from the Server Ada (Lxx) generation, preceded by Server Ampere and succeeded by Server Hopper. The MI455X has no successor listed in the database.

Memory architecture differs fundamentally. The MI455X ships with 432 GB of HBM4 memory on a 24576-bit bus, delivering 23.3 TB/s of bandwidth. The L4 uses 24 GB of GDDR6 on a 192-bit bus, with 300.1 GB/s of bandwidth. The MI455X's memory bandwidth is approximately 77 times higher, and its capacity is 18 times larger. The MI455X runs memory at 1900 MHz with 7.6 Gbps effective speed, whereas the L4 runs at 1563 MHz with 12.5 Gbps effective speed. The L4's faster per-pin data rate does not compensate for the MI455X's vastly wider bus.

Compute resources also differ by an order of magnitude. The MI455X contains 32,768 shading units, 1,024 texture mapping units, and 0 ROPs, with a pixel rate of 0 MPixel/s and a texture rate of 2,457.6 GTexel/s. The L4 contains 7,424 shading units, 240 TMUs, and 80 ROPs, with a pixel rate of 163.2 GPixel/s and a texture rate of 489.6 GTexel/s. The MI455X has no listed RT cores or tensor cores, while the L4 includes 60 RT cores and 240 tensor cores. The MI455X delivers 157.3 TFLOPS in both FP32 and FP16, with a 1:1 ratio. The L4 delivers 30.29 TFLOPS in both FP32 and FP16, also at 1:1. The MI455X's FP32 throughput is roughly 5.2 times the L4's.

Clock behavior differs as well. The MI455X has a base clock of 1000 MHz and a boost clock of 2400 MHz. The L4 operates at a 795 MHz base and 2040 MHz boost. The MI455X runs at a higher base and higher boost, but its power envelope is dramatically larger: 2300 W TDP with a suggested PSU of 2700 W. The L4 draws only 72 W with a suggested PSU of 250 W. The MI455X uses an EAM Module slot width with no power connectors and no display outputs. The L4 is a single-slot card, also with no power connectors and no display outputs. The MI455X uses PCIe 6.0 x16, while the L4 uses PCIe 4.0 x16.

The MI455X lists no API support for DirectX, OpenGL, or Vulkan. The L4 supports DirectX 12 Ultimate (12_2), OpenGL 4.6, and Vulkan 1.4. The MI455X has no production status listed, whereas the L4 is marked Active. The MI455X's release date is 2026-07-22, and the L4's is 2023-03-20. The L4 measures 169 mm in length and 56 mm in height; the MI455X has no dimensions recorded.

Where Each One Wins

The MI455X wins on raw compute scale, memory capacity, and memory bandwidth. Its 432 GB of HBM4 and 23.3 TB/s bandwidth place it in a different class for workloads that need to hold and move massive datasets. Its 157.3 TFLOPS FP32 throughput and 2,457.6 GTexel/s texture rate dwarf the L4's 30.29 TFLOPS and 489.6 GTexel/s. The MI455X also leads in shading units (32,768 vs. 7,424) and TMUs (1,024 vs. 240). The MI455X's PCIe 6.0 interface doubles the L4's PCIe 4.0 link generation, which matters for host-to-device transfer rates.

The L4 wins on efficiency, API compatibility, and physical integration. Its 72 W TDP versus 2300 W means it can operate in far more constrained environments. The L4 draws 3.1% of the MI455X's power budget while still delivering 30.29 TFLOPS, which indicates a much higher performance-per-watt profile. The L4 supports DirectX 12 Ultimate, OpenGL 4.6, and Vulkan 1.4, whereas the MI455X lists no graphics APIs. The L4 also includes 60 RT cores and 240 tensor cores, which the MI455X does not list. The L4's single-slot form factor and 169 mm length make it suitable for dense server configurations, while the MI455X's EAM Module slot width suggests a specialized mounting approach.

The L4's transistor density of 121.8M per mm² exceeds the MI455X's 107.0M per mm², indicating a more compact logic design. The L4's 80 ROPs enable a pixel rate of 163.2 GPixel/s, while the MI455X has 0 ROPs and 0 MPixel/s. The MI455X cannot rasterize or output graphics, so any workload requiring pixel processing falls exclusively to the L4.

The Verdict

The data indicates two accelerators built for entirely different purposes. The AMD Instinct MI455X targets massive-scale compute with 432 GB of HBM4, 23.3 TB/s bandwidth, and 157.3 TFLOPS FP32. Its 2 nm process node, 320,000 million transistors, and 2990 mm² die represent an extreme commitment to scale. The NVIDIA L4 targets efficiency and compatibility with 72 W power draw, a single-slot profile, and full graphics API support. The L4's 95th percentile placement and average benchmark score of 131,072 confirm it as a measured performer in the database. The MI455X's 50th percentile placement with zero benchmarks means no empirical validation exists yet.

The nearest rival data for the L4 shows it performs within 3.2% of the AMD Radeon PRO W6800, NVIDIA A10M, NVIDIA RTX 4000 Ada Generation, and NVIDIA GeForce RTX 3090 Ti. The MI455X has no nearest rivals listed, so its competitive position cannot be established from measurements. The MI455X's release date of 2026-07-22 postdates the L4's 2023-03-20 release, and the MI455X has no production status, while the L4 is Active.

The recorded data suggests the MI455X wins categorically on compute and memory scale, while the L4 wins on efficiency, API support, and measured benchmark validation. Neither card has display outputs, and both lack power connectors. The MI455X's 2300 W TDP requires a 2700 W suggested PSU, while the L4's 72 W TDP needs only a 250 W suggested PSU. The MI455X uses PCIe 6.0 x16, and the L4 uses PCIe 4.0 x16. The MI455X has no RT cores or tensor cores listed, while the L4 has 60 and 240, respectively.

FAQ

Q: Which card has higher FP32 compute?

A: The AMD Instinct MI455X delivers 157.3 TFLOPS FP32, while the NVIDIA L4 delivers 30.29 TFLOPS FP32. The MI455X is roughly 5.2 times higher.

Q: What is the memory capacity difference?

A: The MI455X has 432 GB of HBM4 on a 24576-bit bus with 23.3 TB/s bandwidth. The L4 has 24 GB of GDDR6 on a 192-bit bus with 300.1 GB/s bandwidth.

Q: Does the L4 support graphics APIs?

A: Yes, the L4 supports DirectX 12 Ultimate (12_2), OpenGL 4.6, and Vulkan 1.4. The MI455X lists N/A for all three APIs.

Q: What are the power requirements?

A: The MI455X has a 2300 W TDP and a suggested PSU of 2700 W. The L4 has a 72 W TDP and a suggested PSU of 250 W.

Q: How does the L4 compare to its nearest rivals?

A: The L4 trails the NVIDIA GeForce RTX 3090 Ti by 0.7%, the NVIDIA RTX 4000 Ada Generation by 3.1%, the NVIDIA A10M by 3.1%, and the AMD Radeon PRO W6800 by 3.2%.

Q: What process nodes do the two cards use?

A: The MI455X uses a 2 nm TSMC node with 320,000 million transistors on a 2990 mm² die. The L4 uses a 5 nm TSMC node with 35,800 million transistors on a 294 mm² die.

Specification Differences

| Field | AMD Instinct MI455X | NVIDIA L4 |

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

| 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 | 2040 MHz |

| Memory size | 432 GB | 24 GB |

| Memory type | HBM4 | GDDR6 |

| Memory bus width | 24576 bit | 192 bit |

| Memory bandwidth | 23.3 TB/s | 300.1 GB/s |

| Shading units | 32,768 | 7,424 |

| TMUs | 1,024 | 240 |

| ROPs | 0 | 80 |

| RT cores | Not listed | 60 |

| Tensor cores | Not listed | 240 |

| Pixel rate | 0 MPixel/s | 163.2 GPixel/s |

| Texture rate | 2,457.6 GTexel/s | 489.6 GTexel/s |

| FP32 | 157.3 TFLOPS | 30.29 TFLOPS |

| FP16 | 157.3 TFLOPS (1:1) | 30.29 TFLOPS (1:1) |

| TDP | 2300 W | 72 W |

| Slot width | EAM Module | Single-slot |

| Suggested PSU | 2700 W | 250 W |

| Bus interface | PCIe 6.0 x16 | PCIe 4.0 x16 |

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

| OpenGL support | N/A | 4.6 |

| Vulkan support | N/A | 1.4 |

| Release date | 2026-07-22 | 2023-03-20 |

| Production status | Not listed | Active |

| Predecessor | Radeon Instinct | Server Ampere |

| Successor | Not listed | Server Hopper |

| Percentile vs. all GPUs | 50 | 95 |

| Average benchmark score | 0 | 131,072 |