AMD Instinct MI455X vs AMD Radeon Instinct MI300X Comparison

Head-to-Head Benchmarks

The recorded data shows no direct benchmark scores for either the AMD Instinct MI455X or the AMD Radeon Instinct MI300X. Both parts have an average benchmark score of zero, and both sit at the 50th percentile versus all GPUs in the database. The head-to-head benchmark table is empty, meaning no synthetic or application tests have been logged for either accelerator. Without measured results, the comparison rests entirely on architectural specifications and calculated throughput figures.

What the raw compute figures do indicate is a large gap in raw FP32 output. The MI455X delivers 157.3 TFLOPS of FP32 performance, while the MI300X delivers 81.72 TFLOPS. That places the MI455X at roughly 1.93 times the FP32 throughput of the MI300X, a near doubling of shader-based compute. In FP16, the picture changes dramatically. The MI455X sustains 157.3 TFLOPS at a 1:1 ratio to FP32, meaning it does not gain any extra throughput when moving to reduced precision. The MI300X, by contrast, reaches 653.7 TFLOPS of FP16 using an 8:1 ratio, which gives it over four times the FP16 output of the MI455X. These are the two clearest wins in the comparison: the MI455X for single-precision workloads, and the MI300X for heavily packed half-precision math.

Texture rate also splits the pair. The MI300X has a texture rate of 2,553.6 GTexel/s, slightly ahead of the MI455X at 2,457.6 GTexel/s. The MI455X counters with a higher boost clock of 2400 MHz versus 2100 MHz on the MI300X, and both share the same 1000 MHz base clock. In memory throughput, the MI455X posts 23.3 TB/s of bandwidth against 10.3 TB/s for the MI300X, a lead of roughly 2.26 times. The pixel rate is zero for both, as neither part has output pipelines.

Architecture Differences

The MI455X is built on CDNA 5.0 architecture and uses a chip labeled MI450 256CU. The MI300X uses CDNA 3.0 architecture with the Aqua Vanjaram chip. The process node differs substantially: the MI455X is fabricated on a 2 nm process from TSMC, while the MI300X uses TSMC's 5 nm node. Transistor counts reflect the node jump. The MI455X packs 320,000 million transistors on a 2990 mm² die, giving a transistor density of 107.0M per mm². The MI300X carries 153,000 million transistors on a 1017 mm² die, for a density of 150.4M per mm². The MI455X has more than twice the transistor count and nearly three times the die area, yet its density is lower, an indication that the 2 nm process allows larger physical structures or that the design emphasizes memory and I/O over logic density.

Shading units heavily favor the MI455X: 32768 versus 19456 on the MI300X. Texture mapping units go the other way, with 1216 on the MI300X and 1024 on the MI455X. Neither part has render output units, with a 0 MPixel/s pixel rate recorded for both. Ray tracing cores and tensor cores are not listed for either accelerator, and both have no display outputs.

Memory architecture is a major differentiator. The MI455X uses 432 GB of HBM4 on a 24576-bit bus, while the MI300X uses 192 GB of HBM3 on an 8192-bit bus. Memory clock figures show 1900 MHz (7.6 Gbps effective) for the MI455X and 2525 MHz (10.1 Gbps effective) for the MI300X. The MI455X wins on capacity, bus width, and total bandwidth, while the MI300X runs its memory at a higher effective speed per pin. The MI455X uses an EAM Module slot width, while the MI300X uses an OAM Module. Both are PCIe x16 cards, but the interface generation differs: the MI455X runs PCIe 6.0 x16, and the MI300X runs PCIe 5.0 x16. Neither board has power connectors listed, and both share a "No outputs" designation for display connectivity.

The API support columns are empty or marked N/A for both. The MI455X lists DirectX, OpenGL, and Vulkan as N/A. The MI300X has null entries for all three, so no compute API comparison can be drawn from the database. Power requirements differ sharply. The MI455X has a TDP of 2300 W with a suggested PSU of 2700 W. The MI300X draws 750 W with a suggested PSU of 1150 W. That is a 1550 W difference in TDP and a 1550 W difference in suggested PSU rating.

Where Each One Wins

The MI455X wins in raw FP32 throughput, memory capacity, memory bandwidth, boost clock speed, and transistor count. Its 157.3 TFLOPS of FP32 makes it the stronger part for workloads that rely on single-precision floating point, such as general computational physics, simulation, and any code that does not downshift to FP16. The 432 GB memory pool is more than double the MI300X's 192 GB, which matters for very large model weights or datasets that must stay resident on the accelerator. The 23.3 TB/s bandwidth gives the MI455X a decisive edge in memory-bound tasks that stream large volumes of data per compute operation. The PCIe 6.0 x16 interface also gives it a newer host connection than the MI300X's PCIe 5.0 x16.

The MI300X wins in FP16 throughput, texture rate, and power efficiency. Its 653.7 TFLOPS of FP16 with an 8:1 ratio makes it the stronger choice for half-precision machine learning training and inference workloads that exploit packed math. The 2,553.6 GTexel/s texture rate edges out the MI455X, though both parts are not aimed at graphics work. The 750 W TDP is a fraction of the MI455X's 2300 W, so the MI300X fits into systems with more modest power delivery and cooling. The 1150 W suggested PSU also makes it far easier to deploy in existing server chassis.

The data shows a clean split: the MI455X is a high-bandwidth, high-capacity, high-power compute accelerator for FP32 and large-memory tasks, while the MI300X is a lower-power part with exceptional FP16 throughput for its class.

FAQ

Q: Which accelerator has more FP32 compute power?

A: The AMD Instinct MI455X delivers 157.3 TFLOPS of FP32, which is 1.93 times the 81.72 TFLOPS of the AMD Radeon Instinct MI300X.

Q: Which part has more memory bandwidth?

A: The MI455X has 23.3 TB/s of bandwidth from 432 GB of HBM4 on a 24576-bit bus. The MI300X has 10.3 TB/s from 192 GB of HBM3 on an 8192-bit bus.

Q: Does the MI300X have any compute advantage?

A: Yes. The MI300X reaches 653.7 TFLOPS of FP16 using an 8:1 ratio, while the MI455X sustains 157.3 TFLOPS of FP16 at a 1:1 ratio. The MI300X also has a higher texture rate at 2,553.6 GTexel/s versus 2,457.6 GTexel/s.

Q: What process nodes are used?

A: The MI455X uses a 2 nm TSMC process. The MI300X uses a 5 nm TSMC process.

Q: How do the power requirements compare?

A: The MI455X has a TDP of 2300 W and a suggested PSU of 2700 W. The MI300X has a TDP of 750 W and a suggested PSU of 1150 W.

Q: What interface generations do they use?

A: The MI455X uses PCIe 6.0 x16. The MI300X uses PCIe 5.0 x16.

Specification Differences

| Specification | AMD Instinct MI455X | AMD Radeon Instinct MI300X |

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

| Architecture | CDNA 5.0 | CDNA 3.0 |

| Chip | MI450 256CU | Aqua Vanjaram |

| Process node | 2 nm | 5 nm |

| Transistors | 320,000 million | 153,000 million |

| Die size | 2990 mm² | 1017 mm² |

| Transistor density | 107.0M / mm² | 150.4M / mm² |

| Boost clock | 2400 MHz | 2100 MHz |

| Memory clock | 1900 MHz, 7.6 Gbps effective | 2525 MHz, 10.1 Gbps effective |

| Memory size | 432 GB | 192 GB |

| Memory type | HBM4 | HBM3 |

| Memory bus width | 24576 bit | 8192 bit |

| Memory bandwidth | 23.3 TB/s | 10.3 TB/s |

| Shading units | 32768 | 19456 |

| Texture mapping units | 1024 | 1216 |

| Pixel rate | 0 MPixel/s | 0 MPixel/s |

| FP32 performance | 157.3 TFLOPS | 81.72 TFLOPS |

| FP16 performance | 157.3 TFLOPS (1:1) | 653.7 TFLOPS (8:1) |

| Texture rate | 2,457.6 GTexel/s | 2,553.6 GTexel/s |

| TDP | 2300 W | 750 W |

| Slot width | EAM Module | OAM Module |

| Suggested PSU | 2700 W | 1150 W |

| Bus interface | PCIe 6.0 x16 | PCIe 5.0 x16 |

| Release date | 2026-07-22 | 2023-12-05 |

| Predecessor | Radeon Instinct | FirePro Data Center |

Fields with identical values are omitted. Both parts have no display outputs, no power connectors listed, no RT cores, no tensor cores, and no dimensions recorded.

The Verdict

The AMD Instinct MI455X is the higher-performing accelerator on paper for FP32 compute, memory capacity, and memory bandwidth. Its 157.3 TFLOPS of FP32, 432 GB of HBM4, and 23.3 TB/s of bandwidth place it clearly ahead of the MI300X in single-precision and memory-heavy scenarios. The 2 nm process, PCIe 6.0 interface, and 32768 shading units reinforce that position. The cost of that capability is a 2300 W TDP and a 2700 W suggested PSU, which makes it a specialized part for systems built around extreme power delivery.

The AMD Radeon Instinct MI300X is the better choice for FP16-heavy workloads and for deployments with power constraints. Its 653.7 TFLOPS of FP16 throughput at an 8:1 ratio is over four times the MI455X's FP16 output, and its 750 W TDP with a 1150 W suggested PSU fits into standard server infrastructure. The 192 GB of HBM3 and 10.3 TB/s bandwidth are smaller than the MI455X, but the part's efficiency profile and earlier 2023 release date make it a practical option where the MI455X's power envelope is not feasible.

The data does not show a universal winner. The MI455X dominates FP32, capacity, bandwidth, and interface generation. The MI300X dominates FP16, texture rate, and power efficiency. Buyers should match the accelerator to the workload: large single-precision models and massive memory footprints point to the MI455X, while packed half-precision training and lower power ceilings point to the MI300X.