AMD Instinct MI455X vs AMD Radeon RX 9070 XT Comparison

Head-to-Head Benchmarks

The recorded data offers a direct comparison challenge: the AMD Instinct MI455X has no benchmark scores in the database, while the AMD Radeon RX 9070 XT has a full set of recorded results. The MI455X registers an average benchmark score of 0, placing it at the 50th percentile of all GPUs. The RX 9070 XT, by contrast, holds a 55th percentile rank with an average benchmark score of 13,543.

The RX 9070 XT's strongest recorded result is its Geekbench Vulkan score of 65,879, which indicates strong graphics API performance. Its OpenCL score of 17,428 shows compute capability, while the PassMark G3D score of 26,795 reflects overall graphics processing. The PassMark GPU compute result of 15,864 further quantifies raw compute throughput.

The RX 9070 XT also delivers specific DirectX performance numbers across multiple API versions. PassMark DirectX 9 scores 353, DirectX 11 scores 292, DirectX 10 scores 154, and DirectX 12 scores 78. The 3DMark Steel Nomad DX12 test records 7,260 points, and PassMark G2D scores 1,328.

Because the MI455X has no benchmark entries, the head-to-head comparison is one-sided. The data shows the RX 9070 XT as the only card with measurable performance results. The MI455X's lack of scores means any direct numerical comparison is impossible from the database. The MI455X does hold a percentile rank of 50, which places it below the RX 9070 XT's 55th percentile, but without actual scores this rank appears derived from its hardware specifications rather than tested performance.

The nearest rivals for the RX 9070 XT provide context for its scores. The AMD Radeon HD 7770M averages 13,536, a 0.1% difference. The NVIDIA GeForce GTX 570 averages 13,515, a 0.2% difference. The NVIDIA P106-090 averages 13,470, a 0.5% difference. The AMD Radeon Pro 555 averages 13,407, a 1% difference. These four cards sit within a narrow band around the RX 9070 XT's average, indicating the RX 9070 XT's average score of 13,543 is closely matched by these older or lower-tier parts.

The MI455X has no nearest rivals listed, reinforcing that the database holds no comparable performance data for it. The wins tally shows 0 wins for the MI455X and 0 wins for the RX 9070 XT, which reflects the empty head-to-head benchmark array rather than a tied result.

Architecture Differences

The MI455X and RX 9070 XT use fundamentally different GPU architectures from AMD. The MI455X is built on CDNA 5.0, while the RX 9070 XT uses RDNA 4.0. The MI455X belongs to the Instinct (MIx) generation, designed for compute workloads. The RX 9070 XT belongs to the Navi IV (RX 9000) series, aimed at graphics rendering.

Manufacturing processes differ significantly. The MI455X uses a 2 nm process from TSMC, while the RX 9070 XT uses a 4 nm process, also from TSMC. The MI455X integrates 320,000 million transistors across a 2,990 mm² die, yielding a transistor density of 107.0M per mm². The RX 9070 XT contains 53,900 million transistors on a 357 mm² die, with a density of 151.0M per mm². The MI455X's die is substantially larger, but its density is lower due to the massive transistor count spread across the larger area.

The MI455X's chip is designated MI450 256CU, and the RX 9070 XT uses Navi 48. Clock behavior diverges: the MI455X runs a base clock of 1000 MHz with a boost up to 2400 MHz, while the RX 9070 XT runs a base of 1660 MHz, a game clock of 2400 MHz, and a boost of 2970 MHz. The RX 9070 XT operates at higher clock speeds across the board.

Memory architecture presents the largest gap. The MI455X includes 432 GB of HBM4 memory on a 24,576-bit bus, delivering 23.3 TB/s of bandwidth. The RX 9070 XT has 16 GB of GDDR6 on a 256-bit bus, with 644.6 GB/s bandwidth. The MI455X's memory bandwidth is roughly 36 times greater, and its capacity is 27 times higher.

Compute resources differ by an order of magnitude. The MI455X has 32,768 shading units and 1,024 texture mapping units, but 0 ROPs and a pixel rate of 0 MPixel/s. The RX 9070 XT has 4,096 shading units, 256 TMUs, 128 ROPs, and a pixel rate of 380.2 GPixel/s. The MI455X's texture rate is 2,457.6 GTexel/s versus 760.3 GTexel/s for the RX 9070 XT.

Floating-point throughput shows the MI455X's compute focus. The MI455X delivers 157.3 TFLOPS for both FP32 and FP16 (1:1 ratio). The RX 9070 XT delivers 48.66 TFLOPS for both FP32 and FP16. The MI455X is 3.2 times higher in FP32 and FP16. The RX 9070 XT includes 64 ray tracing cores; the MI455X lists no RT cores.

Power and connectivity differ sharply. The MI455X has a TDP of 2300 W with a suggested PSU of 2700 W, no power connectors (an EAM Module slot width), and PCIe 6.0 x16. The RX 9070 XT has a TDP of 304 W, suggested PSU of 700 W, dual 8-pin power connectors, dual-slot width, and PCIe 5.0 x16. The RX 9070 XT offers display outputs (1x HDMI 2.1b, 3x DisplayPort 2.1a); the MI455X has no outputs. API support also differs: the RX 9070 XT supports DirectX 12 Ultimate (12_2), OpenGL 4.6, and Vulkan 1.4, while the MI455X lists N/A for all three.

FAQ

Q: Which card has higher FP32 compute throughput?

A: The MI455X delivers 157.3 TFLOPS FP32, which is 3.2 times the RX 9070 XT's 48.66 TFLOPS.

Q: How much memory does each card have?

A: The MI455X has 432 GB of HBM4 on a 24,576-bit bus with 23.3 TB/s bandwidth. The RX 9070 XT has 16 GB of GDDR6 on a 256-bit bus with 644.6 GB/s bandwidth.

Q: Does the MI455X support DirectX or Vulkan?

A: No. The MI455X lists N/A for DirectX, OpenGL, and Vulkan. The RX 9070 XT supports DirectX 12 Ultimate (12_2), OpenGL 4.6, and Vulkan 1.4.

Q: What is the process node for each chip?

A: The MI455X uses a 2 nm TSMC process, while the RX 9070 XT uses a 4 nm TSMC process.

Q: Which card has ray tracing cores?

A: The RX 9070 XT has 64 ray tracing cores. The MI455X lists no ray tracing cores.

Q: What benchmark scores exist for the MI455X?

A: The database contains no benchmark results for the MI455X, and its average benchmark score is 0. The RX 9070 XT has 10 recorded benchmark scores with an average of 13,543.

The Verdict

The data points to a clear division of purpose. The MI455X is a compute accelerator with no display outputs, no graphics API support, and a massive memory pool of 432 GB HBM4 with 23.3 TB/s bandwidth. Its 157.3 TFLOPS FP32 and FP16 throughput, 32,768 shading units, and 2,457.6 GTexel/s texture rate position it for data-center or scientific workloads where graphics rendering is irrelevant. Its 2300 W TDP and 2700 W suggested PSU confirm it is not a desktop gaming card.

The RX 9070 XT is a rasterization and ray tracing GPU. It has 64 RT cores, 128 ROPs, a pixel rate of 380.2 GPixel/s, and full DirectX 12 Ultimate, OpenGL 4.6, and Vulkan 1.4 support. Its display outputs (1x HDMI 2.1b, 3x DisplayPort 2.1a) and dual-slot form factor make it suitable for standard graphics workloads. Its 16 GB GDDR6 and 644.6 GB/s bandwidth serve gaming and workstation rendering.

The benchmark evidence favors the RX 9070 XT only because it has recorded results, all of which cluster around the 55th percentile. The MI455X's 50th percentile with zero scores indicates no tested performance exists. A user requiring raw compute density should look to the MI455X based on its specification sheet. A user requiring graphics output, ray tracing, or standard API support must choose the RX 9070 XT, as the MI455X offers none of those features.

The MI455X's transistor count of 320,000 million versus 53,900 million and die size of 2,990 mm² versus 357 mm² show the scale difference. The RX 9070 XT's higher transistor density of 151.0M per mm² versus 107.0M per mm² indicates a more compact design, but the MI455X's absolute resources dwarf it. The decision rests on workload type, not on benchmark scores.

Specification Differences

| Specification | AMD Instinct MI455X | AMD Radeon RX 9070 XT |

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

| Architecture | CDNA 5.0 | RDNA 4.0 |

| Generation | Instinct (MIx) | Navi IV (RX 9000) |

| Chip | MI450 256CU | Navi 48 |

| Process Node | 2 nm | 4 nm |

| Transistors | 320,000 million | 53,900 million |

| Die Size | 2990 mm² | 357 mm² |

| Base Clock | 1000 MHz | 1660 MHz |

| Boost Clock | 2400 MHz | 2970 MHz |

| Game Clock | N/A | 2400 MHz |

| Memory Size | 432 GB | 16 GB |

| Memory Type | HBM4 | GDDR6 |

| Memory Bus | 24576 bit | 256 bit |

| Memory Bandwidth | 23.3 TB/s | 644.6 GB/s |

| Shading Units | 32768 | 4096 |

| TMUs | 1024 | 256 |

| ROPs | 0 | 128 |

| RT Cores | N/A | 64 |

| Pixel Rate | 0 MPixel/s | 380.2 GPixel/s |

| Texture Rate | 2,457.6 GTexel/s | 760.3 GTexel/s |

| FP32 | 157.3 TFLOPS | 48.66 TFLOPS |

| FP16 | 157.3 TFLOPS | 48.66 TFLOPS |

| TDP | 2300 W | 304 W |

| Slot Width | EAM Module | Dual-slot |

| Power Connectors | None | 2x 8-pin |

| Suggested PSU | 2700 W | 700 W |

| Bus Interface | PCIe 6.0 x16 | PCIe 5.0 x16 |

| Display Outputs | No outputs | 1x HDMI 2.1b, 3x DisplayPort 2.1a |

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

| OpenGL | N/A | 4.6 |

| Vulkan | N/A | 1.4 |

| Release Date | 2026-07-22 | 2025-03-05 |

Where Each One Wins

The MI455X wins in every raw compute metric. Its FP32 and FP16 throughput of 157.3 TFLOPS exceeds the RX 9070 XT by 3.2 times. Its texture rate of 2,457.6 GTexel/s is 3.2 times higher than 760.3 GTexel/s. Memory capacity of 432 GB versus 16 GB, bandwidth of 23.3 TB/s versus 644.6 GB/s, and bus width of 24,576 bits versus 256 bits make it the clear choice for memory-bound workloads. Its 32,768 shading units and 1,024 TMUs outnumber the RX 9070 XT's 4,096 and 256. The PCIe 6.0 x16 interface provides a newer bus standard than the RX 9070 XT's PCIe 5.0 x16.

The RX 9070 XT wins in all graphics-specific categories. It has 128 ROPs versus 0, a pixel rate of 380.2 GPixel/s versus 0 MPixel/s, and 64 RT cores where the MI455X has none. It supports DirectX 12 Ultimate, OpenGL 4.6, and Vulkan 1.4, while the MI455X supports no graphics APIs. It provides display outputs, which the MI455X lacks entirely. Its boost clock of 2970 MHz exceeds the MI455X's 2400 MHz, and its base clock of 1660 MHz is higher than 1000 MHz. The RX 9070 XT's 304 W TDP and 700 W suggested PSU make it practical for standard systems, versus the MI455X's 2300 W TDP and 2700 W PSU requirement.

For benchmark performance, only the RX 9070 XT has data. Its average score of 13,543 sits at the 55th percentile, with nearest rivals within 1%. The MI455X has no recorded scores and a 50th percentile rank. Users needing tested gaming or workstation graphics performance have only the RX 9070 XT as a verified option. Users needing massive compute and memory resources can rely on the MI455X's specifications, but no benchmark confirmation exists in the database.