AMD Radeon Instinct MI25 vs AMD Radeon RX 6900 XT Comparison

FAQ

Q: Which GPU is faster in the OpenCL benchmark recorded in the database?

A: The AMD Radeon RX 6900 XT delivers a Geekbench OpenCL score of 187,673, while the AMD Radeon Instinct MI25 scores 68,562. The RX 6900 XT leads by 63.5% in this test.

Q: How does the Radeon Instinct MI25 compare to its nearest rivals in average benchmark score?

A: The MI25 has an average benchmark score of 68,562, placing it at the 90th percentile of all GPUs. It trails the Intel Arc A770 by 0.4% (68,809), the NVIDIA CMP 90HX by 0.6% (69,000), the AMD Radeon Pro WX 8200 by 1.9% (69,870), and the NVIDIA Quadro P6000 by 2% (69,986).

Q: What is the memory configuration difference between these two cards?

A: Both cards have 16 GB of memory, but the MI25 uses HBM2 on a 2048-bit bus with 436.2 GB/s bandwidth, while the RX 6900 XT uses GDDR6 on a 256-bit bus with 512.0 GB/s bandwidth.

Q: Which card has higher shading unit and texture unit counts?

A: The RX 6900 XT has 5,120 shading units and 320 texture mapping units, compared to the MI25's 4,096 shading units and 256 TMUs. The RX 6900 XT also has 128 ROPs versus 64 on the MI25.

Q: Do these cards support different PCIe interfaces?

A: Yes. The MI25 uses PCIe 3.0 x16, while the RX 6900 XT uses PCIe 4.0 x16, doubling the available bandwidth for data transfers between the GPU and the host system.

Q: What is the production status and release timeline for each card?

A: The MI25 was released on June 26, 2017, and is end-of-life. The RX 6900 XT was released on October 27, 2020, and is also end-of-life. The RX 6900 XT has a successor (Navi III), while the MI25 does not.

Architecture Differences

The AMD Radeon Instinct MI25 is built on the Vega 10 chip using GCN 5.0 architecture, fabricated on a 14 nm process at GlobalFoundries. It contains 12,500 million transistors on a 495 mm² die, resulting in a transistor density of 25.3 million per mm². The RX 6900 XT uses the Navi 21 chip with RDNA 2.0 architecture, manufactured on TSMC's 7 nm process. It packs 26,800 million transistors into a 520 mm² die, achieving a density of 51.5 million per mm², more than double the MI25's density.

Clock behavior differs substantially. The MI25 runs at a base clock of 1400 MHz and a boost clock of 1500 MHz. The RX 6900 XT has a base clock of 1825 MHz, a game clock of 2015 MHz, and a boost clock of 2250 MHz. This directly impacts throughput: the MI25 delivers 12.29 TFLOPS FP32 and 24.58 TFLOPS FP16 (2:1 ratio), while the RX 6900 XT delivers 23.04 TFLOPS FP32 and 46.08 TFLOPS FP16 (2:1 ratio).

Memory architecture is a key differentiator. The MI25 employs HBM2 with a 2048-bit bus and 436.2 GB/s bandwidth, while the RX 6900 XT uses GDDR6 on a 256-bit bus with 512.0 GB/s bandwidth. The MI25's memory runs at 852 MHz (1704 Mbps effective), whereas the RX 6900 XT's memory runs at 2000 MHz (16 Gbps effective).

The RX 6900 XT adds 80 ray tracing cores, which the MI25 lacks entirely. The MI25 has no display outputs, making it a compute-only accelerator. The RX 6900 XT includes 1x HDMI 2.1, 2x DisplayPort 1.4a, and 1x USB Type-C outputs. API support also differs: the MI25 supports DirectX 12 (12_1), OpenGL 4.6, and Vulkan 1.3, while the RX 6900 XT supports DirectX 12 Ultimate (12_2), OpenGL 4.6, and Vulkan 1.4.

Head-to-Head Benchmarks

The database contains one direct head-to-head comparison between these two cards: Geekbench OpenCL. In this test, the RX 6900 XT scores 187,673 against the MI25's 68,562, a delta of 63.5% in favor of the newer card. This is a massive margin, reflecting the generational leap in compute performance.

The MI25's average benchmark score of 68,562 places it at the 90th percentile of all GPUs, meaning it outperforms 90% of the database's recorded GPUs. The RX 6900 XT has a lower percentile ranking at 86, despite a higher average score of 50,951. This discrepancy exists because the RX 6900 XT's average includes multiple benchmark results across various tests (DirectX 9, 10, 11, 12, Metal, Vulkan, and compute), while the MI25 only has a single OpenCL entry.

The RX 6900 XT's Geekbench Metal score is 177,021, and its Vulkan score is 148,525. Its Passmark G3D score is 26,732, with a GPU compute score of 14,547. These additional metrics show consistent strength across different APIs. The MI25's sole benchmark result, 68,562 in OpenCL, is within 0.4% of the Intel Arc A770's 68,809 and 0.6% of the NVIDIA CMP 90HX's 69,000, placing it in the same performance tier as those accelerators.

The RX 6900 XT's nearest rivals include the NVIDIA CMP 50HX at 51,790 (1.6% higher), the AMD Radeon RX Vega 64 at 50,001 (1.9% lower), the NVIDIA GeForce RTX 5070 Ti at 49,957 (2% lower), and the Intel Arc A550M at 49,737 (2.4% lower). This clustering indicates the RX 6900 XT's average performance sits in a tight band with those cards, despite its large OpenCL advantage over the MI25.

Specification Differences

| Specification | AMD Radeon Instinct MI25 | AMD Radeon RX 6900 XT |

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

| Chip | Vega 10 | Navi 21 |

| Architecture | GCN 5.0 | RDNA 2.0 |

| Process node | 14 nm | 7 nm |

| Foundry | GlobalFoundries | TSMC |

| Transistors | 12,500 million | 26,800 million |

| Die size | 495 mm² | 520 mm² |

| Transistor density | 25.3M / mm² | 51.5M / mm² |

| Base clock | 1400 MHz | 1825 MHz |

| Boost clock | 1500 MHz | 2250 MHz |

| Game clock | None | 2015 MHz |

| Memory clock | 852 MHz (1704 Mbps effective) | 2000 MHz (16 Gbps effective) |

| Memory type | HBM2 | GDDR6 |

| Memory bus width | 2048 bit | 256 bit |

| Memory bandwidth | 436.2 GB/s | 512.0 GB/s |

| Shading units | 4096 | 5120 |

| TMUs | 256 | 320 |

| ROPs | 64 | 128 |

| Ray tracing cores | None | 80 |

| Pixel rate | 96.00 GPixel/s | 288.0 GPixel/s |

| Texture rate | 384.0 GTexel/s | 720.0 GTexel/s |

| FP32 | 12.29 TFLOPS | 23.04 TFLOPS |

| FP16 | 24.58 TFLOPS (2:1) | 46.08 TFLOPS (2:1) |

| Bus interface | PCIe 3.0 x16 | PCIe 4.0 x16 |

| Display outputs | No outputs | 1x HDMI 2.1, 2x DisplayPort 1.4a, 1x USB Type-C |

| DirectX support | 12 (12_1) | 12 Ultimate (12_2) |

| Vulkan support | 1.3 | 1.4 |

| Slot width | Dual-slot | Triple-slot |

| Height | 111 mm (4.4 inches) | 120 mm (4.7 inches) |

| Width | Not specified | 50 mm (2 inches) |

| TDP | 300 W | 300 W |

| Power connectors | 2x 8-pin | 2x 8-pin |

| Suggested PSU | 700 W | 700 W |

| Release date | 2017-06-26 | 2020-10-27 |

| Predecessor | FirePro Data Center | Navi |

| Successor | None | Navi III |

| Launch MSRP | None | 999 USD |

Both cards share a 300 W TDP, 700 W suggested PSU, 2x 8-pin power connectors, 16 GB memory capacity, 267 mm length, and end-of-life production status.

The Verdict

The data clearly favors the RX 6900 XT for virtually every measurable performance metric. In the only direct comparison available, the RX 6900 XT leads by 63.5% in Geekbench OpenCL. It also has a 87.5% higher FP32 throughput (23.04 vs 12.29 TFLOPS), 100% higher FP16 throughput (46.08 vs 24.58 TFLOPS), 200% higher pixel rate (288.0 vs 96.00 GPixel/s), and 87.5% higher texture rate (720.0 vs 384.0 GTexel/s).

The MI25's 90th percentile ranking versus the RX 6900 XT's 86th percentile reflects a difference in benchmark methodology, not real-world capability. The MI25's single OpenCL score of 68,562 places it in a competitive tier with the Intel Arc A770 and NVIDIA CMP 90HX, but the RX 6900 XT's OpenCL score of 187,673 is in a completely different performance class.

For compute workloads measured by OpenCL, the RX 6900 XT is the clear choice. The MI25's advantage is limited to its HBM2 memory bus width (2048-bit vs 256-bit), which may benefit certain memory-bandwidth-sensitive tasks, but the RX 6900 XT's higher memory bandwidth (512.0 vs 436.2 GB/s) negates this in raw throughput terms.

The RX 6900 XT's launch MSRP was 999 USD, while the MI25 had no recorded launch MSRP.

Where Each One Wins

The RX 6900 XT wins in:

• OpenCL compute performance (63.5% ahead)
• FP32 and FP16 raw throughput (87.5% and 100% higher respectively)
• Pixel fill rate (3x higher)
• Texture fill rate (87.5% higher)
• Memory bandwidth (17.4% higher)
• Ray tracing capability (80 cores vs none)
• API compatibility (DirectX 12 Ultimate, Vulkan 1.4)
• Display connectivity (full output suite vs none)
• PCIe bandwidth (4.0 vs 3.0)

The MI25 wins in:

• Memory bus width (2048-bit vs 256-bit), which may reduce latency in certain access patterns
• Transistor density per mm² is lower, but this is not an advantage
• Percentile ranking (90th vs 86th), though this is an artifact of benchmark count
• Physical footprint height (111 mm vs 120 mm) and dual-slot vs triple-slot design, making it easier to fit in some chassis

For a system builder choosing between these two end-of-life cards, the RX 6900 XT is the superior choice for any workload involving OpenCL, graphics, ray tracing, or general-purpose compute. The MI25 remains relevant only for specialized scenarios requiring HBM2's wide bus in a compute-only form factor with no display output, such as headless server deployments where the RX 6900 XT's display outputs and triple-slot cooler are unnecessary. The RX 6900 XT's 16 GB GDDR6 memory and 512.0 GB/s bandwidth provide ample capacity for modern workloads, while the MI25's 16 GB HBM2 with 436.2 GB/s bandwidth offers lower bandwidth but potentially better efficiency for certain memory patterns.