AMD Instinct MI350P vs AMD Instinct MI455X Comparison

Where Each One Wins

The AMD Instinct MI350P and AMD Instinct MI455X occupy distinct positions in the accelerator landscape, with the MI455X dominating across every measurable compute dimension. The recorded data shows the MI455X holds a decisive advantage in raw throughput metrics, while the MI350P offers a more conventional dual-slot form factor with a 600 W TDP and a single 16-pin power connector. The MI455X, by contrast, is an EAM Module with a 2300 W TDP and no external power connectors, indicating a fundamentally different deployment target.

Benchmark results indicate the MI455X wins outright in shading throughput, texture processing, and memory bandwidth. The MI350P does not win a single comparative category in the database. However, the MI350P presents a lower power envelope and a standard PCIe 5.0 x16 interface, which may suit systems not designed for the MI455X's PCIe 6.0 x16 connection and 2700 W suggested power supply. The MI455X's 432 GB HBM4 memory dwarfs the MI350P's 144 GB HBM3e, making the larger card the clear choice for capacity-bound workloads. The MI350P's 8192 shading units and 512 texture mapping units are exactly one quarter of the MI455X's 32768 shading units and 1024 TMUs, reinforcing a consistent 4:1 ratio across compute resources.

Architecture Differences

The two accelerators diverge significantly at the architecture level. The MI350P uses CDNA 4.0 on a 3 nm TSMC process, while the MI455X uses CDNA 5.0 on a 2 nm TSMC process. The MI455X integrates 320,000 million transistors on a 2990 mm² die, yielding a transistor density of 107.0M per mm². The MI350P contains 73,000 million transistors on a 1190 mm² die, with a density of 61.3M per mm². This represents a 4.38x transistor count advantage for the MI455X and a 2.51x die area advantage, while the density improvement of 1.75x reflects the newer 2 nm node.

Clock behavior also differs. Both cards share a 1000 MHz base clock, but the MI455X boosts to 2400 MHz versus the MI350P's 2200 MHz, a 9.1% higher boost frequency. Memory configurations are starkly different: the MI350P uses HBM3e at 2000 MHz with an 8 Gbps effective data rate across an 8192-bit bus, producing 8.19 TB/s of bandwidth. The MI455X uses HBM4 at 1900 MHz with a 7.6 Gbps effective rate across a 24576-bit bus, delivering 23.3 TB/s. The MI455X's memory bus is exactly three times wider, and its bandwidth advantage is 2.84x despite the modestly lower memory clock.

The MI455X doubles the texture mapping units to 1024 and quadruples shading units to 32768. Both parts report 0 MPixel/s pixel rates and no display outputs, consistent with compute-only accelerators. The MI455X uses PCIe 6.0 x16, while the MI350P uses PCIe 5.0 x16. Neither card supports DirectX, OpenGL, or Vulkan, confirming their exclusive compute focus. Physical dimensions differ substantially: the MI350P measures 267 mm by 111 mm by 40 mm, while the MI455X has no recorded dimensions due to its EAM Module form factor.

Head-to-Head Benchmarks

The database contains no direct head-to-head benchmark entries, and both cards show an average benchmark score of zero with a 50th percentile ranking among all GPUs. However, the specification data enables a direct comparison of theoretical peak performance. The MI455X delivers 157.3 TFLOPS of FP32 and FP16 (1:1) compute, against the MI350P's 36.04 TFLOPS in both formats. This is a 4.36x advantage for the MI455X, closely matching the 4x shading unit ratio and the 9.1% boost clock advantage.

Texture fill rate follows a similar pattern. The MI455X achieves 2,457.6 GTexel/s, while the MI350P reaches 1,126.4 GTexel/s. Although the MI455X has exactly twice the TMUs, its higher boost clock yields a 2.18x fill rate advantage. Memory bandwidth shows the largest relative difference: 23.3 TB/s versus 8.19 TB/s, a 2.84x gap driven by the triple-width memory bus.

The MI455X also leads in memory capacity by 3x, with 432 GB versus 144 GB, and uses a newer memory type (HBM4 versus HBM3e). The MI350P counters with a higher memory clock (2000 MHz versus 1900 MHz) and a faster effective data rate (8 Gbps versus 7.6 Gbps), but these advantages are overwhelmed by the MI455X's wider bus. Power consumption scales with performance: the MI455X's 2300 W TDP is 3.83x the MI350P's 600 W TDP, and the suggested power supply jumps from 1000 W to 2700 W.

Release timing favors the MI455X, which launched on 2026-07-22, approximately 2.5 months after the MI350P's 2026-05-06 release. Both cards descend from the Radeon Instinct line and belong to the Instinct (MIx) generation. The MI350P's die area of 1190 mm² is already large, but the MI455X's 2990 mm² die represents an extreme physical footprint that explains its EAM Module packaging.

FAQ

Q: Which accelerator has higher FP32 compute performance?

A: The MI455X delivers 157.3 TFLOPS FP32, which is 4.36x higher than the MI350P's 36.04 TFLOPS. Both cards achieve the same FP32 and FP16 figures, indicating 1:1 ratio.

Q: How do memory configurations compare?

A: The MI455X uses 432 GB of HBM4 with a 24576-bit bus and 23.3 TB/s bandwidth. The MI350P uses 144 GB of HBM3e with an 8192-bit bus and 8.19 TB/s bandwidth. The MI455X provides 3x capacity and 2.84x bandwidth.

Q: What are the power requirements for each card?

A: The MI350P has a 600 W TDP with a 1000 W suggested power supply and uses a single 16-pin connector. The MI455X has a 2300 W TDP with a 2700 W suggested power supply and uses no external power connectors, relying on its EAM Module interface.

Q: Do these accelerators support graphics APIs?

A: No. Both cards report N/A for DirectX, OpenGL, and Vulkan, and they have no display outputs. They are compute-only accelerators.

Q: What is the transistor density difference?

A: The MI455X achieves 107.0M transistors per mm² on TSMC's 2 nm process, while the MI350P reaches 61.3M per mm² on 3 nm. The MI455X integrates 320,000 million transistors versus 73,000 million in the MI350P.

Q: Which card has a higher boost clock?

A: The MI455X boosts to 2400 MHz, 9.1% higher than the MI350P's 2200 MHz boost. Both share a 1000 MHz base clock.

The Verdict

The recorded data indicates a clear performance hierarchy: the AMD Instinct MI455X outperforms the MI350P in every compute category. Its 157.3 TFLOPS FP32 throughput, 2,457.6 GTexel/s texture rate, 23.3 TB/s memory bandwidth, and 432 GB capacity represent the top tier of the database's accelerator specifications. The MI455X's 4.36x compute advantage and 3x memory capacity advantage make it the superior choice for workloads that can utilize its extreme power envelope and EAM Module form factor.

The MI350P, with 36.04 TFLOPS FP32, 1,126.4 GTexel/s, 8.19 TB/s bandwidth, and 144 GB capacity, suits environments requiring a dual-slot card with standard PCIe 5.0 x16 compatibility. Its 600 W TDP and 1000 W suggested power supply align with conventional server infrastructure, whereas the MI455X demands the 2700 W suggested supply and PCIe 6.0 x16 interface. The MI350P's 3 nm process and 1190 mm² die offer a more modest transistor budget, but its 61.3M per mm² density trails the MI455X's 107.0M per mm² on 2 nm.

For memory-bound applications, the MI455X's HBM4 with a 24576-bit bus provides 23.3 TB/s, a figure that no other accelerator in this comparison approaches. The MI350P's HBM3e at 8.19 TB/s is capable but fundamentally limited by its 8192-bit bus. The MI455X's 2400 MHz boost clock also contributes to its lead, while the MI350P's 2200 MHz boost remains the lower ceiling.

The choice depends on system constraints and workload requirements. The MI455X is the performance leader, but its 2300 W TDP and EAM Module packaging restrict it to specialized platforms. The MI350P offers a conventional installation path with its 267 mm length, dual-slot width, and 16-pin power connector. Both cards lack graphics APIs and display outputs, confirming their dedicated compute roles. The database shows the MI455X as the definitive performance winner, with the MI350P serving as the more integrable alternative for power-constrained deployments.