AMD Radeon Instinct MI308X vs NVIDIA Rubin GPU Comparison

The Verdict

The database places both accelerators at the 50th percentile among all recorded GPUs, with no benchmark scores or nearest rivals listed for either part. The recorded data therefore does not support a performance winner. What the data does show is a clear separation in design targets. AMD Radeon Instinct MI308X pairs a 5 nm CDNA 3.0 architecture with 192 GB of HBM3 and a 750 W thermal envelope. NVIDIA Rubin GPU uses a 3 nm Rubin architecture with 288 GB of HBM4 and a 2300 W envelope. Any selection decision must be made on workload fit, not on raw score comparison, since the database contains no measured results for either.

The NVIDIA part is the only one with an active production status. AMD's part has no recorded production status. The Rubin GPU also carries a release date of 2025-12-31, while the MI308X is dated 2023-12-05. For parties constrained by availability timelines, the Rubin GPU appears positioned as the current shipping product. The MI308X, with an earlier release date and no active status, appears to be the older entry.

The AMD part targets memory capacity per watt: 192 GB at 750 W yields a density of 0.256 GB per watt. The NVIDIA part delivers 288 GB at 2300 W, which is 0.125 GB per watt. If the workload is memory-capacity bound and power constrained, the MI308X data looks favorable. If the workload is bandwidth or compute bound, the Rubin GPU's larger bus, faster memory type, and higher FP32 throughput point to it as the more capable part, accepting its power requirement.

Architecture Differences

The two accelerators diverge at the node level. The MI308X uses TSMC's 5 nm process with 153,000 million transistors on a 1017 mm² die, producing a transistor density of 150.4M per mm². The Rubin GPU uses TSMC's 3 nm process with 336,000 million transistors on a 1456 mm² die, for a density of 230.8M per mm². The Rubin GPU holds more than double the transistor count, a larger die, and a 53.5% higher transistor density.

Architecture names confirm separate lineages. The MI308X runs CDNA 3.0 under the chip name Aqua Vanjaram, part of the Radeon Instinct (MIx) generation. The Rubin GPU runs the Rubin architecture under the chip name GR100, part of the Server Rubin (Rxx) generation. The AMD part lists its predecessor as FirePro Data Center; the NVIDIA part lists Server Blackwell as its predecessor.

Memory architecture differs substantially. The MI308X uses HBM3 with 192 GB, an 8192 bit bus, and 10.3 TB/s bandwidth. The Rubin GPU uses HBM4 with 288 GB, a 16384 bit bus, and 22.1 TB/s bandwidth. That is double the bus width and more than double the bandwidth. Clock behavior also differs. The MI308X has a 1000 MHz base and 2100 MHz boost. The Rubin GPU has a 700 MHz base and 2267 MHz boost, a lower floor but a higher ceiling.

The compute block layout is not a simple scaling. The MI308X has 19,456 shading units, 1,216 TMUs, and no recorded ROPs, pixel rate, or tensor cores. The Rubin GPU has 28,672 shading units, 896 TMUs, 24 ROPs, and 896 tensor cores. The AMD part has more TMUs despite fewer shading units. The NVIDIA part records a pixel rate of 54.41 GPixel/s while the AMD part records 0 MPixel/s. Texture rates are 2,553.6 GTexel/s for AMD versus 2,031.2 GTexel/s for NVIDIA. The AMD part leads in texture rate; the NVIDIA part leads in pixel rate and adds tensor cores.

FP32 and FP16 ratios also differ. The MI308X lists FP32 at 81.72 TFLOPS and FP16 at 653.7 TFLOPS with an 8:1 ratio. The Rubin GPU lists FP32 at 130.0 TFLOPS and FP16 at 260.0 TFLOPS with a 2:1 ratio. The AMD part has a much larger FP16 advantage relative to its FP32, while the NVIDIA part has a 59.1% higher FP32 figure.

Package and interface details differ. The MI308X is an OAM Module with no power connectors and a suggested PSU of 1150 W. The Rubin GPU is an SXM Module with a suggested PSU of 2700 W and a PCIe 6.0 x16 interface. The MI308X uses PCIe 5.0 x16. Neither part has display outputs. The NVIDIA part records its API support as N/A for DirectX, OpenGL, and Vulkan; the AMD part records null values for those fields.

FAQ

Q: Which accelerator has more memory capacity?

A: The NVIDIA Rubin GPU has 288 GB of HBM4, while the AMD Radeon Instinct MI308X has 192 GB of HBM3.

Q: What is the memory bandwidth difference?

A: The Rubin GPU reaches 22.1 TB/s over a 16384 bit bus. The MI308X reaches 10.3 TB/s over an 8192 bit bus. The Rubin GPU provides more than double the bandwidth.

Q: Which part has higher FP32 throughput?

A: The Rubin GPU lists 130.0 TFLOPS FP32. The MI308X lists 81.72 TFLOPS FP32. The NVIDIA part leads by 59.1%.

Q: Which part has higher FP16 throughput?

A: The MI308X lists 653.7 TFLOPS FP16 with an 8:1 ratio. The Rubin GPU lists 260.0 TFLOPS FP16 with a 2:1 ratio. The AMD part leads in raw FP16 throughput.

Q: What are the power requirements?

A: The MI308X has a 750 W TDP and a suggested PSU of 1150 W. The Rubin GPU has a 2300 W TDP and a suggested PSU of 2700 W.

Q: Are these parts production-ready?

A: The Rubin GPU has an active production status and a release date of 2025-12-31. The MI308X has no recorded production status and a release date of 2023-12-05.

Specification Differences

| Field | AMD Radeon Instinct MI308X | NVIDIA Rubin GPU |

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

| Chip | Aqua Vanjaram | GR100 |

| Architecture | CDNA 3.0 | Rubin |

| Generation | Radeon Instinct (MIx) | Server Rubin (Rxx) |

| Process node | 5 nm | 3 nm |

| Transistors | 153,000 million | 336,000 million |

| Die size | 1017 mm² | 1456 mm² |

| Transistor density | 150.4M / mm² | 230.8M / mm² |

| Base clock | 1000 MHz | 700 MHz |

| Boost clock | 2100 MHz | 2267 MHz |

| Memory clock | 2525 MHz, 10.1 Gbps effective | 2695 MHz, 10.8 Gbps effective |

| Memory size | 192 GB | 288 GB |

| Memory type | HBM3 | HBM4 |

| Memory bus | 8192 bit | 16384 bit |

| Memory bandwidth | 10.3 TB/s | 22.1 TB/s |

| Shading units | 19,456 | 28,672 |

| TMUs | 1,216 | 896 |

| ROPs | 0 | 24 |

| Tensor cores | null | 896 |

| Pixel rate | 0 MPixel/s | 54.41 GPixel/s |

| Texture rate | 2,553.6 GTexel/s | 2,031.2 GTexel/s |

| FP32 | 81.72 TFLOPS | 130.0 TFLOPS |

| FP16 | 653.7 TFLOPS (8:1) | 260.0 TFLOPS (2:1) |

| TDP | 750 W | 2300 W |

| Slot width | OAM Module | SXM Module |

| Power connectors | None | null |

| Suggested PSU | 1150 W | 2700 W |

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

| Display outputs | No outputs | No outputs |

| DirectX | null | N/A |

| OpenGL | null | N/A |

| Vulkan | null | N/A |

| Production status | null | Active |

| Release date | 2023-12-05 | 2025-12-31 |

| Predecessor | FirePro Data Center | Server Blackwell |

Head-to-Head Benchmarks

The database lists no recorded benchmark scores for either accelerator, and the head-to-head table is empty. The comparison must rely on specification-derived measurements. The largest NVIDIA advantages appear in memory bandwidth, FP32 throughput, and transistor scale. The Rubin GPU's 22.1 TB/s bandwidth is more than double the MI308X's 10.3 TB/s. Its FP32 figure of 130.0 TFLOPS exceeds the AMD part's 81.72 TFLOPS by 59.1%. Its transistor count of 336,000 million is 119.6% higher than the MI308X's 153,000 million.

The largest AMD advantages appear in texture rate and FP16 throughput. The MI308X's 2,553.6 GTexel/s beats the Rubin GPU's 2,031.2 GTexel/s by 25.7%. Its FP16 figure of 653.7 TFLOPS is 151.4% higher than the Rubin GPU's 260.0 TFLOPS, though the AMD part achieves this with an 8:1 ratio versus the NVIDIA part's 2:1 ratio. The AMD part also has more TMUs (1,216 versus 896) and a lower TDP (750 W versus 2300 W).

Clock behavior favors different scenarios. The MI308X has a higher base clock at 1000 MHz versus 700 MHz. The Rubin GPU has a higher boost clock at 2267 MHz versus 2100 MHz. The memory clock also favors NVIDIA at 2695 MHz versus 2525 MHz, with effective rates of 10.8 Gbps versus 10.1 Gbps.

Form factor and interface differences matter for system integration. The MI308X uses an OAM Module with no power connectors and PCIe 5.0 x16. The Rubin GPU uses an SXM Module with PCIe 6.0 x16. The suggested PSU scales with TDP: 1150 W for AMD, 2700 W for NVIDIA.

Neither part supports display outputs, confirming their server-oriented role. The AMD part records no production status, while the NVIDIA part is marked active. The release dates place the MI308X at 2023-12-05 and the Rubin GPU at 2025-12-31, a gap of roughly two years. The data profile suggests the MI308X is the earlier, lower-power design with a strong FP16 ratio, while the Rubin GPU is the newer, higher-power design with a wider memory bus, tensor cores, and higher FP32 throughput. Without measured benchmarks, the database cannot confirm which part delivers better real-world performance, but the specification data clearly differentiates their intended operating points.