AMD Instinct MI355X vs AMD Radeon RX 6450M Comparison

The Verdict

The AMD Instinct MI355X and AMD Radeon RX 6450M serve entirely different purposes, and the recorded data confirms they should never be cross-shopped. The MI355X is an accelerator module with a 1400 W TDP, 288 GB of HBM3e memory, and CDNA 4.0 architecture, designed for compute workloads where massive parallel throughput and memory capacity are paramount. The RX 6450M is a 50 W mobile GPU with RDNA 2.0 architecture, 4 GB of GDDR6 memory, and a PCIe 4.0 x4 interface, built for portable devices needing basic graphics output. The MI355X has no display outputs and no graphics API support, while the RX 6450M supports DirectX 12 Ultimate, OpenGL 4.6, and Vulkan 1.4. The data shows these are not competitors; they are complementary products for different markets. The MI355X targets server and datacenter compute, while the RX 6450M targets mobile consumer and professional portable systems.

Architecture Differences

The architectural split is stark. The MI355X uses the MI350 256CU chip built on a 3 nm process at TSMC, featuring 185,000 million transistors on a 2380 mm² die, yielding a transistor density of 77.7M per mm². The RX 6450M uses the Navi 24 chip on a 6 nm process, also at TSMC, with 5,400 million transistors on a 107 mm² die, for a density of 50.5M per mm². The MI355X employs CDNA 4.0, a compute-focused architecture, while the RX 6450M uses RDNA 2.0, a graphics-oriented design. The MI355X has 16,384 shading units, 1,024 TMUs, and no ROPs, pixel rate, or ray tracing cores listed. The RX 6450M has 768 shading units, 48 TMUs, 32 ROPs, and 12 ray tracing cores. The MI355X supports FP32 and FP16 at 78.64 TFLOPS with a 1:1 ratio, while the RX 6450M delivers 3.779 TFLOPS FP32 and 7.557 TFLOPS FP16 with a 2:1 ratio. The MI355X has no graphics API support, no display outputs, and is a 102 mm by 165 mm OAM Module. The RX 6450M is an IGP with portable device dependent display outputs and full graphics API coverage.

Head-to-Head Benchmarks

The database contains no direct head-to-head benchmark results for these two parts, and the wins count is zero for both. This absence itself is informative: the MI355X has an avgBenchmarkScore of 0 and the RX 6450M also has an avgBenchmarkScore of 0, with both sitting at the 50th percentile versus all GPUs. With no recorded benchmark data, the comparison must rely on specification differences. The MI355X delivers 78.64 TFLOPS FP32, which is 20.8 times the RX 6450M's 3.779 TFLOPS. Its texture rate of 2,457.6 GTexel/s is 20.8 times the RX 6450M's 118.1 GTexel/s. Memory bandwidth shows the largest gap: 8.19 TB/s versus 128.0 GB/s, a 64-fold difference. The MI355X has 288 GB of HBM3e on an 8192-bit bus, while the RX 6450M has 4 GB of GDDR6 on a 64-bit bus. Clock speeds tell a different story: the RX 6450M has a higher base clock at 2000 MHz versus 1000 MHz, and a slightly higher boost at 2460 MHz versus 2400 MHz. The RX 6450M also lists a game clock of 2220 MHz, which the MI355X lacks entirely. The RX 6450M's pixel rate of 78.72 GPixel/s is real, while the MI355X has a pixel rate of 0 MPixel/s. The MI355X has no ROPs, making pixel output impossible, which aligns with its compute-only design.

FAQ

Q: Which GPU has more shading units?

A: The AMD Instinct MI355X has 16,384 shading units, while the AMD Radeon RX 6450M has 768 shading units.

Q: How do the memory sizes compare?

A: The MI355X has 288 GB of HBM3e memory on an 8192-bit bus, while the RX 6450M has 4 GB of GDDR6 on a 64-bit bus.

Q: What is the TDP difference?

A: The MI355X has a TDP of 1400 W with a suggested PSU of 1800 W, while the RX 6450M has a TDP of 50 W and no suggested PSU listed.

Q: Which GPU supports graphics APIs?

A: The RX 6450M supports DirectX 12 Ultimate (12_2), OpenGL 4.6, and Vulkan 1.4. The MI355X has no graphics API support listed (N/A for all three).

Q: What are the process nodes?

A: The MI355X uses a 3 nm process at TSMC, while the RX 6450M uses a 6 nm process at TSMC.

Q: Do both GPUs have display outputs?

A: No. The MI355X has no display outputs, while the RX 6450M has portable device dependent display outputs.

Where Each One Wins

The MI355X wins decisively in raw compute throughput. Its FP32 performance of 78.64 TFLOPS dwarfs the RX 6450M's 3.779 TFLOPS. Its FP16 performance is identical at 78.64 TFLOPS, while the RX 6450M reaches 7.557 TFLOPS. The MI355X's texture rate of 2,457.6 GTexel/s is 20.8 times the RX 6450M's 118.1 GTexel/s. Memory capacity and bandwidth are overwhelmingly in the MI355X's favor: 288 GB versus 4 GB, and 8.19 TB/s versus 128.0 GB/s. The MI355X uses a PCIe 5.0 x16 interface, while the RX 6450M uses PCIe 4.0 x4. The MI355X has a larger die at 2380 mm² versus 107 mm², and a higher transistor count at 185,000 million versus 5,400 million.

The RX 6450M wins in graphics-specific features and practical mobile deployment. It has 32 ROPs and a pixel rate of 78.72 GPixel/s, while the MI355X has zero ROPs and zero pixel rate. The RX 6450M includes 12 ray tracing cores, which the MI355X does not list. The RX 6450M supports DirectX 12 Ultimate, OpenGL 4.6, and Vulkan 1.4, enabling real-time graphics workloads. Its base clock of 2000 MHz is double the MI355X's 1000 MHz, and its boost clock of 2460 MHz edges out the MI355X's 2400 MHz. The RX 6450M also lists a game clock of 2220 MHz. The RX 6450M is an IGP with a 50 W TDP, making it suitable for portable devices, while the MI355X is an OAM Module with a 1400 W TDP and no display outputs. The RX 6450M has a production status of Active, while the MI355X has no production status listed. The RX 6450M was released on 2023-01-03, while the MI355X was released on 2025-06-11.

Specification Differences

| Specification | AMD Instinct MI355X | AMD Radeon RX 6450M |

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

| Chip | MI350 256CU | Navi 24 |

| Architecture | CDNA 4.0 | RDNA 2.0 |

| Generation | Instinct (MIx) | Navi Mobile (RX 6000M) |

| Process Node | 3 nm | 6 nm |

| Transistors | 185,000 million | 5,400 million |

| Die Size | 2380 mm² | 107 mm² |

| Transistor Density | 77.7M / mm² | 50.5M / mm² |

| Base Clock | 1000 MHz | 2000 MHz |

| Boost Clock | 2400 MHz | 2460 MHz |

| Game Clock | None | 2220 MHz |

| Memory Clock | 2000 MHz, 8 Gbps effective | 2000 MHz, 16 Gbps effective |

| Memory Size | 288 GB | 4 GB |

| Memory Type | HBM3e | GDDR6 |

| Memory Bus Width | 8192 bit | 64 bit |

| Memory Bandwidth | 8.19 TB/s | 128.0 GB/s |

| Shading Units | 16384 | 768 |

| TMUs | 1024 | 48 |

| ROPs | 0 | 32 |

| Ray Tracing Cores | None | 12 |

| Pixel Rate | 0 MPixel/s | 78.72 GPixel/s |

| Texture Rate | 2,457.6 GTexel/s | 118.1 GTexel/s |

| FP32 | 78.64 TFLOPS | 3.779 TFLOPS |

| FP16 | 78.64 TFLOPS (1:1) | 7.557 TFLOPS (2:1) |

| TDP | 1400 W | 50 W |

| Slot Width | OAM Module | IGP |

| Power Connectors | None | None |

| Suggested PSU | 1800 W | None |

| Bus Interface | PCIe 5.0 x16 | PCIe 4.0 x4 |

| Display Outputs | No outputs | Portable Device Dependent |

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

| OpenGL | N/A | 4.6 |

| Vulkan | N/A | 1.4 |

| Dimensions | 102 mm (4 inches) x 165 mm (6.5 inches) | None listed |

| Production Status | None | Active |

| Release Date | 2025-06-11 | 2023-01-03 |

| Predecessor | Radeon Instinct | Polaris Mobile |

The data confirms two divergent design philosophies. The MI355X allocates all resources to compute density, memory bandwidth, and throughput, sacrificing display output, graphics APIs, and pixel processing. The RX 6450M balances graphics features, ray tracing, and portability, with a lower power envelope and full API support. The MI355X's 8192-bit memory bus and 8.19 TB/s bandwidth serve massive data movement, while the RX 6450M's 64-bit bus and 128.0 GB/s bandwidth serve lightweight mobile workloads. The 3 nm process of the MI355X enables 77.7M transistors per mm², while the RX 6450M's 6 nm process achieves 50.5M per mm². The MI355X has no launch MSRP, and the RX 6450M also has no launch MSRP listed. Both parts occupy the 50th percentile versus all GPUs with a benchmark score of zero, reflecting the absence of recorded benchmark data for either product.