AMD Instinct MI308X vs NVIDIA Rubin GPU Comparison

Head-to-Head Benchmarks

The database contains no direct benchmark scores for either the AMD Instinct MI308X or the NVIDIA Rubin GPU. Both parts record zero benchmark entries, zero average scores, and zero head-to-head comparisons. Consequently, no measured frame-rate, compute, or ray-tracing deltas can be reported from the recorded data. What can be quantified is the theoretical peak throughput and memory performance derived from each part's specification sheet.

In FP32 compute, the NVIDIA Rubin GPU delivers 130.0 TFLOPS, which is 59.1% higher than the AMD Instinct MI308X's 81.72 TFLOPS. The Rubin part also leads in FP16 with 260.0 TFLOPS at a 2:1 ratio, compared to the MI308X's 81.72 TFLOPS at a 1:1 ratio. The difference in FP16 is substantial: the Rubin GPU offers 218.2% more FP16 throughput. This places the Rubin GPU clearly ahead in raw floating-point work for both single-precision and half-precision workloads.

Memory bandwidth tells a similar story. The NVIDIA Rubin GPU reaches 22.1 TB/s across a 16384-bit bus using HBM4, while the AMD Instinct MI308X provides 5.32 TB/s across an 8192-bit bus using HBM3. The Rubin GPU's bandwidth is 315.4% higher. Memory capacity also favors the Rubin GPU: 288 GB versus 192 GB, a 50.0% advantage. For memory-bound workloads such as large model inference, the Rubin GPU's aggregate bandwidth and capacity are decisive on paper.

The AMD Instinct MI308X does hold wins in certain specification categories. Its texture rate is 2,553.6 GTexel/s, which is 25.7% higher than the Rubin GPU's 2,031.2 GTexel/s. The MI308X also operates with a higher base clock: 1000 MHz versus 700 MHz, a 42.9% advantage. Its boost clock is lower, at 2100 MHz versus 2267 MHz, meaning the Rubin GPU's boost clock is 8.0% higher. The MI308X has more texture mapping units (1216 versus 896, a 35.7% advantage), while the Rubin GPU has more shading units (28672 versus 19456, a 47.4% advantage). The MI308X reports no ROPs and a pixel rate of 0 MPixel/s, whereas the Rubin GPU has 24 ROPs and a pixel rate of 54.41 GPixel/s. Neither part has display outputs, and both list no applicable graphics APIs.

Pixel fill rate is exclusively present on the Rubin side, as the MI308X records zero ROPs. The Rubin GPU's 54.41 GPixel/s is the only rasterization throughput figure in the comparison. Given that both are server accelerators with no display outputs, this difference is unlikely to affect typical compute workloads.

Architecture Differences

The two accelerators come from different process nodes and foundries. The AMD Instinct MI308X uses a 5 nm process at TSMC, while the NVIDIA Rubin GPU uses a 3 nm process at TSMC. The Rubin GPU's die is larger at 1456 mm², compared to the MI308X's 1017 mm², a 43.2% larger die area. Transistor counts differ even more dramatically: the Rubin GPU integrates 336,000 million transistors, versus 153,000 million on the MI308X, a 119.6% higher count. Transistor density also favors the Rubin GPU at 230.8M per mm², compared to 150.4M per mm², a 53.5% higher density.

The chip identities are distinct: the MI308X is built on the Aqua Vanjaram chip with CDNA 3.0 architecture, while the Rubin GPU uses the GR100 chip with the Rubin architecture. The generations also differ: the MI308X belongs to the Instinct (MIx) generation, and the Rubin GPU belongs to the Server Rubin (Rxx) generation. The MI308X's predecessor is Radeon Instinct; the Rubin GPU's predecessor is Server Blackwell.

Memory architecture separates the two parts significantly. The MI308X uses HBM3 with 192 GB and an 8192-bit bus. The Rubin GPU uses HBM4 with 288 GB and a 16384-bit bus. The memory clock also differs: the MI308X runs at 1300 MHz with 5.2 Gbps effective, while the Rubin GPU runs at 2695 MHz with 10.8 Gbps effective. The Rubin GPU's memory clock is 107.3% higher in effective transfer rate. These memory system differences align with the bandwidth and capacity gaps noted previously.

Compute resource distribution varies. The MI308X has 19456 shading units and 1216 TMUs, but zero ROPs and no listed tensor cores. The Rubin GPU has 28672 shading units, 896 TMUs, 24 ROPs, and 896 tensor cores. The MI308X therefore has more texture units, while the Rubin GPU has more shaders, the only ROPs in the comparison, and an explicit tensor core count.

Power and physical specifications diverge sharply. The MI308X has a TDP of 750 W and fits an OAM Module slot with no power connectors and a suggested PSU of 1150 W. The Rubin GPU has a TDP of 2300 W, uses an SXM Module, and requires a suggested PSU of 2700 W. The Rubin GPU's TDP is 206.7% higher, and its suggested PSU is 134.8% higher. Bus interfaces also differ: the MI308X uses PCIe 5.0 x16, while the Rubin GPU uses PCIe 6.0 x16.

Release timing places the MI308X earlier: its release date is 2023-12-05, while the Rubin GPU's release date is 2025-12-31. The Rubin GPU has an active production status, while the MI308X has no recorded production status. Both parts have no launch MSRP recorded, and both lack display outputs.

The architecture names reflect different design philosophies. CDNA 3.0 is AMD's compute-focused lineage, while Rubin is NVIDIA's server architecture following Server Blackwell. The absence of DirectX, OpenGL, and Vulkan support on both parts confirms they are not intended for client graphics workloads.

The Verdict

The recorded data indicates that the NVIDIA Rubin GPU is the more capable accelerator on paper across most compute metrics. Its FP32 throughput of 130.0 TFLOPS exceeds the MI308X's 81.72 TFLOPS by 59.1%. Its FP16 throughput of 260.0 TFLOPS exceeds the MI308X's 81.72 TFLOPS by 218.2%. Memory bandwidth of 22.1 TB/s is 315.4% higher, and capacity of 288 GB is 50.0% higher. Shading units are 47.4% more numerous, and the Rubin GPU is the only part with tensor cores and ROPs.

The AMD Instinct MI308X holds advantages in texture rate (2,553.6 GTexel/s versus 2,031.2 GTexel/s, a 25.7% lead), TMU count (1216 versus 896, a 35.7% lead), base clock (1000 MHz versus 700 MHz, a 42.9% lead), and lower power draw (750 W versus 2300 W). The MI308X also uses a smaller die (1017 mm² versus 1456 mm²) and fewer transistors (153,000 million versus 336,000 million). For deployments where texture throughput or power envelope is the binding constraint, the MI308X is the better fit. For workloads that scale with FP32, FP16, memory bandwidth, or memory capacity, the Rubin GPU is the stronger selection.

The absence of benchmark scores means no measured performance data exists in the database for either part. The verdict rests entirely on specification-derived figures. The Rubin GPU's higher transistor density, larger memory subsystem, and explicit tensor core presence indicate a design aimed at large-scale compute and AI workloads. The MI308X's higher texture rate and lower TDP suggest a design that prioritizes texture-heavy operations and more modest power budgets.

FAQ

Q: Which GPU has higher FP32 performance?

A: The NVIDIA Rubin GPU, at 130.0 TFLOPS, is 59.1% higher than the AMD Instinct MI308X's 81.72 TFLOPS.

Q: How much memory bandwidth does each accelerator provide?

A: The NVIDIA Rubin GPU provides 22.1 TB/s over a 16384-bit HBM4 interface. The AMD Instinct MI308X provides 5.32 TB/s over an 8192-bit HBM3 interface.

Q: What are the memory capacities of the two parts?

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

Q: Do either of these accelerators have display outputs or graphics API support?

A: Neither part has display outputs. Both list no applicable DirectX, OpenGL, or Vulkan support.

Q: What process nodes do the two GPUs use?

A: The AMD Instinct MI308X uses a 5 nm process at TSMC. The NVIDIA Rubin GPU uses a 3 nm process at TSMC.

Q: Which GPU has more shading units and which has more texture mapping units?

A: The NVIDIA Rubin GPU has 28672 shading units, which is 47.4% more than the MI308X's 19456. The AMD Instinct MI308X has 1216 TMUs, which is 35.7% more than the Rubin GPU's 896.

Where Each One Wins

The NVIDIA Rubin GPU wins in FP32 compute, FP16 compute, memory bandwidth, memory capacity, shading unit count, transistor count, transistor density, die size, ROP count, tensor core presence, pixel rate, boost clock, and bus interface generation. Its FP32 lead of 59.1% and FP16 lead of 218.2% make it the clear choice for floating-point-heavy workloads. Its 22.1 TB/s bandwidth and 288 GB capacity suit large model training and inference tasks that require rapid data movement and substantial resident data.

The AMD Instinct MI308X wins in texture rate (25.7% higher), TMU count (35.7% higher), base clock (42.9% higher), and lower power requirements (750 W versus 2300 W). Its 2,553.6 GTexel/s texture rate benefits workloads that sample textures heavily, such as certain rendering pipelines or convolution-like operations. The lower TDP and 1150 W suggested PSU make it easier to integrate into power-constrained systems, while the Rubin GPU's 2300 W TDP and 2700 W suggested PSU demand more substantial power infrastructure.

The two parts occupy different positions in the database: the MI308X is an older release (2023-12-05) with a smaller transistor budget, while the Rubin GPU is a newer release (2025-12-31) with an active production status. For users prioritizing raw compute and memory capacity, the Rubin GPU is the data-supported choice. For users prioritizing texture throughput and lower power draw, the MI308X is the data-supported choice. No measured benchmark scores exist for either part, so these selections are based solely on specification figures from the database.