AMD Instinct MI455X vs NVIDIA Rubin GPU Comparison

Head-to-Head Benchmarks

The recorded database contains no benchmark scores for either the AMD Instinct MI455X or the NVIDIA Rubin GPU. Both entries carry an average benchmark score of zero and hold the 50th percentile position among all GPUs in the database. With zero wins recorded for each part, the head-to-head comparison rests entirely on the architectural and specification data rather than measured performance deltas.

The absence of benchmark results means neither accelerator can claim a measured advantage in compute workloads. The FP32 figures, however, indicate a theoretical peak for the MI455X at 157.3 TFLOPS, which is 27.3 TFLOPS higher than the Rubin GPU's 130.0 TFLOPS. That translates to a 21% lead for AMD in single-precision floating-point throughput. In FP16 operations, the relationship reverses: the Rubin GPU delivers 260.0 TFLOPS with a 2:1 ratio, while the MI455X matches its FP32 number at 157.3 TFLOPS with a 1:1 ratio. NVIDIA's part therefore offers 102.7 TFLOPS more half-precision compute, a 65% advantage.

Texture throughput also favors the MI455X. Its 2,457.6 GTexel/s rate exceeds the Rubin GPU's 2,031.2 GTexel/s by 426.4 GTexel/s, a 21% margin. The pixel rate comparison is more complex: the MI455X records 0 MPixel/s due to having no ROPs, while the Rubin GPU posts 54.41 GPixel/s. Memory bandwidth sits close between the two, with the MI455X reaching 23.3 TB/s versus 22.1 TB/s for the Rubin GPU, a 1.2 TB/s difference.

Architecture Differences

The two accelerators diverge fundamentally in their underlying design philosophies. The AMD Instinct MI455X uses the CDNA 5.0 architecture, built on a 2 nm TSMC process. Its chip, designated MI450 256CU, packs 320,000 million transistors across a die size of 2990 mm². The transistor density calculates to 107.0M per mm². NVIDIA's Rubin GPU employs the Rubin architecture on a 3 nm TSMC node, with the GR100 chip containing 336,000 million transistors on a 1456 mm² die. That yields a transistor density of 230.8M per mm², more than double the AMD part's density.

The core configurations reflect different strategies. The MI455X fields 32,768 shading units, 1,024 texture mapping units, and zero ROPs. The Rubin GPU counters with 28,672 shading units, 896 TMUs, and 24 ROPs. AMD also includes no tensor cores in its specification, while NVIDIA lists 896 tensor cores. Both parts use HBM4 memory, but the MI455X carries 432 GB across a 24,576-bit bus, whereas the Rubin GPU has 288 GB on a 16,384-bit bus. The larger bus width gives AMD the bandwidth edge despite fewer memory stacks.

Clock behavior differs notably. The MI455X has a 1000 MHz base clock and a 2400 MHz boost, with memory running at 1900 MHz (7.6 Gbps effective). The Rubin GPU starts lower at 700 MHz base but boosts to 2267 MHz, with memory at 2695 MHz (10.8 Gbps effective). The AMD part's higher base and boost clocks contribute to its FP32 lead, while NVIDIA's faster memory clock partially compensates for the narrower bus.

Where Each One Wins

The AMD Instinct MI455X wins in scenarios that demand raw single-precision throughput, memory capacity, and memory bandwidth. Its 157.3 TFLOPS FP32 peak suits workloads where FP32 is the dominant precision, such as certain scientific simulations or graphics-style compute tasks that do not benefit from reduced precision. The 432 GB memory capacity is the largest in this comparison, accommodating larger models or datasets that would exceed the Rubin GPU's 288 GB allocation. The 23.3 TB/s bandwidth also edges ahead, which helps memory-bound kernels that stream large volumes of data.

The NVIDIA Rubin GPU wins in half-precision compute and any workload that leverages tensor cores. Its 260.0 TFLOPS FP16 (2:1) represents a substantial advantage for AI training and inference, where mixed-precision arithmetic is standard practice. The 896 tensor cores provide dedicated hardware for matrix operations, a feature entirely absent from the MI455X specification. The Rubin GPU's 24 ROPs and 54.41 GPixel/s pixel rate also give it a functional graphics pipeline, though both cards lack display outputs and target server environments.

The texture rate advantage for AMD (2,457.6 GTexel/s vs 2,031.2 GTexel/s) indicates stronger texel-processing capability, which matters in texture-heavy compute or rendering workloads. However, the MI455X's zero ROPs means it cannot complete the pixel-rendering pipeline, limiting its utility in traditional rasterization tasks. The Rubin GPU's combination of ROPs, tensor cores, and higher FP16 throughput positions it for AI-centric deployments, while the MI455X targets capacity-heavy FP32 compute.

Specification Differences

The two parts differ across nearly every major specification field. The process node is 2 nm for AMD versus 3 nm for NVIDIA, both from TSMC. Transistor counts are close, with NVIDIA at 336,000 million and AMD at 320,000 million, but the die size gap is large: 2990 mm² for the MI455X against 1456 mm² for the Rubin GPU. This makes the AMD die more than twice as large physically, while NVIDIA achieves higher density per square millimeter.

Base clocks differ by 300 MHz (1000 MHz vs 700 MHz), and boost clocks differ by 133 MHz (2400 MHz vs 2267 MHz). Memory clock rates show a 795 MHz difference at the base frequency (1900 MHz vs 2695 MHz), though the effective rates of 7.6 Gbps and 10.8 Gbps tell the same story. Shading units total 32,768 for AMD versus 28,672 for NVIDIA, a 4,096-unit difference. TMUs sit at 1,024 versus 896, a 128-unit difference. ROPs present the starkest contrast: 0 for AMD versus 24 for NVIDIA.

Memory capacity differs by 144 GB (432 GB vs 288 GB), and bus width differs by 8,192 bits (24,576 vs 16,384). Bandwidth shows a 1.2 TB/s gap (23.3 vs 22.1). FP32 throughput favors AMD by 27.3 TFLOPS, while FP16 favors NVIDIA by 102.7 TFLOPS. Texture rate favors AMD by 426.4 GTexel/s, and pixel rate favors NVIDIA by 54.41 GPixel/s. Both share a 2300 W TDP and a 2700 W suggested PSU. The MI455X uses an EAM Module slot, while the Rubin GPU uses an SXM Module. Both connect via PCIe 6.0 x16 and have no display outputs. The AMD part has no production status listed, while NVIDIA's is marked Active. Release dates differ by roughly seven months: the MI455X lists 2026-07-22, and the Rubin GPU lists 2025-12-31.

FAQ

Q: Which accelerator has higher FP32 throughput?

A: The AMD Instinct MI455X delivers 157.3 TFLOPS FP32, which is 27.3 TFLOPS higher than the NVIDIA Rubin GPU's 130.0 TFLOPS.

Q: How does half-precision performance compare?

A: The NVIDIA Rubin GPU reaches 260.0 TFLOPS FP16 (2:1), while the AMD MI455X achieves 157.3 TFLOPS FP16 (1:1). NVIDIA leads by 102.7 TFLOPS.

Q: Which GPU offers more memory capacity?

A: The AMD MI455X has 432 GB of HBM4 memory, 144 GB more than the NVIDIA Rubin GPU's 288 GB.

Q: Are both accelerators built on the same process node?

A: No. The AMD MI455X uses a 2 nm TSMC process, while the NVIDIA Rubin GPU uses a 3 nm TSMC process.

Q: Do either of these GPUs have tensor cores?

A: The NVIDIA Rubin GPU includes 896 tensor cores. The AMD MI455X specification lists no tensor cores.

Q: What is the power requirement for these parts?

A: Both the AMD MI455X and the NVIDIA Rubin GPU have a 2300 W TDP and a suggested PSU rating of 2700 W.