NVIDIA B300 SXM6 AC vs NVIDIA Rubin GPU Comparison

Head-to-Head Benchmarks

The database currently holds a single OpenCL benchmark score for the NVIDIA B300 SXM6 AC, recorded at 369,831 points. This places the B300 SXM6 AC in the 100th percentile of all GPUs tracked, meaning no other tested accelerator has surpassed it in this workload. The NVIDIA Rubin GPU, by contrast, has no recorded benchmark scores in the database at this time. Its average benchmark score sits at zero, and its percentile rank is listed at 50, which is a placeholder value until measurements are populated. Consequently, no head-to-head benchmark comparisons can be drawn directly between these two parts from the recorded data.

However, the B300 SXM6 AC can be contextualized against its nearest rivals. The database shows the B300 SXM6 AC is 7% ahead of the NVIDIA B200, which averages 345,482 points. Against the NVIDIA H200 NVL, the lead expands to 10.4%, with that accelerator scoring 334,891 points. The AMD Instinct MI300X trails by 16.3%, posting an average of 317,994 points. The largest gap among the listed rivals is against the NVIDIA L40S, where the B300 SXM6 AC is 25% faster, as the L40S averages 295,763 points. These delta percentages confirm that the B300 SXM6 AC is the top performer in its immediate competitive set, with a commanding lead even over the B200, which is its closest challenger.

For the Rubin GPU, the absence of benchmark data means its performance cannot be quantified relative to any rival. The database lists no nearest rivals for this part, and its win count in head-to-head comparisons is zero. Until benchmark results are submitted and recorded, any performance assertion would be speculative. The data indicates only that the Rubin GPU is an active product with a pending measurement profile.

Architecture Differences

The architectural gap between the B300 SXM6 AC and the Rubin GPU is substantial, starting with the manufacturing process. The B300 SXM6 AC uses a 5 nm node from TSMC, while the Rubin GPU is built on a 3 nm node, also from TSMC. This process shrink contributes directly to the transistor density difference: the B300 SXM6 AC packs 208,000 million transistors across a 1628 mm² die, yielding a density of 127.8 million transistors per square millimeter. The Rubin GPU integrates 336,000 million transistors on a smaller 1456 mm² die, achieving a density of 230.8 million transistors per square millimeter. This represents a 61.5% higher transistor count on a 10.6% smaller die, enabled entirely by the denser 3 nm process.

The chip designs themselves diverge in generation and architecture. The B300 SXM6 AC is built around the GB110 chip, using the Blackwell Ultra architecture, and belongs to the Server Blackwell (Bxx) generation. The Rubin GPU uses the GR100 chip, adopts the Rubin architecture, and is classified under the Server Rubin (Rxx) generation. The Rubin GPU is designated as the successor to the Server Blackwell line, while the B300 SXM6 AC lists Server Hopper as its predecessor and Server Rubin as its successor. This places the two parts on opposite sides of a generational transition.

Clock behavior differs significantly between the two. The B300 SXM6 AC has a base clock of 1665 MHz and a boost clock of 2032 MHz. The Rubin GPU has a much lower base clock of 700 MHz but a higher boost clock of 2267 MHz. This suggests the Rubin GPU relies on aggressive boost behavior rather than sustained base clocks. Memory clocks also differ: the B300 SXM6 AC runs at 2000 MHz with 8 Gbps effective data rate, while the Rubin GPU runs at 2695 MHz with 10.8 Gbps effective.

Memory architecture shows a major leap. Both parts carry 288 GB of memory, but the type and bandwidth differ. The B300 SXM6 AC uses HBM3e over an 8192-bit bus, delivering 8.19 TB/s of bandwidth. The Rubin GPU uses HBM4 over a 16384-bit bus, doubling the bus width and pushing bandwidth to 22.1 TB/s. That is a 170% increase in memory bandwidth, which is critical for data-intensive server workloads.

Compute resources also scale upward. The B300 SXM6 AC has 18,944 shading units, 592 texture mapping units, 24 ROPs, and 592 tensor cores. The Rubin GPU increases shading units to 28,672, TMUs to 896, and tensor cores to 896, while keeping ROPs at 24. These counts translate into higher theoretical rates. The B300 SXM6 AC achieves 48.77 GPixel/s pixel rate and 1,202.9 GTexel/s texture rate. The Rubin GPU reaches 54.41 GPixel/s and 2,031.2 GTexel/s, representing gains of 11.6% and 68.9%, respectively.

Raw compute throughput is where the Rubin GPU pulls away clearly. The B300 SXM6 AC delivers 76.99 TFLOPS of FP32 and 76.99 TFLOPS of FP16 with a 1:1 ratio. The Rubin GPU delivers 130.0 TFLOPS of FP32 and 260.0 TFLOPS of FP16 with a 2:1 ratio. In FP32, the Rubin GPU is 68.8% faster. In FP16, it is 237.7% faster. The 2:1 FP16 ratio indicates dedicated tensor throughput scaling that the B300 SXM6 AC does not offer.

Power envelopes diverge as well. The B300 SXM6 AC has a TDP of 1100 W and a suggested PSU of 1500 W. The Rubin GPU has a TDP of 2300 W and a suggested PSU of 2700 W. The Rubin GPU more than doubles the power draw, which is consistent with its higher transistor count and boost clock. Both are SXM modules with no display outputs, and both use PCIe 6.0 x16 as the bus interface. Neither part exposes DirectX, OpenGL, or Vulkan APIs, confirming their server-only positioning.

The Verdict

The recorded data supports a clear split between the two accelerators. The B300 SXM6 AC is a proven performer with a benchmark score in the 100th percentile and a 7% lead over the closest rival, the NVIDIA B200. Its 288 GB of HBM3e memory and 8.19 TB/s bandwidth are sufficient for current-generation server workloads, and its 1100 W TDP is more manageable in existing infrastructure.

The Rubin GPU is architecturally superior on paper, with a 3 nm process, 336,000 million transistors, 130.0 TFLOPS FP32, 260.0 TFLOPS FP16, and 22.1 TB/s of HBM4 bandwidth. However, the database contains no benchmark results for this part. Its percentile rank of 50 is a default value, not a measured outcome. The data indicates the Rubin GPU is active, but performance validation is pending.

For buyers choosing strictly from measured data, the B300 SXM6 AC is the only option with verified performance. For buyers prioritizing raw architectural specifications and future-proofing, the Rubin GPU offers higher theoretical limits. The absence of Rubin benchmarks means the B300 SXM6 AC remains the top-ranked accelerator in the database, holding the 100th percentile position. The Rubin GPU cannot claim any performance advantage until its results are recorded.

FAQ

Q: What is the recorded benchmark score for the NVIDIA B300 SXM6 AC?

A: The B300 SXM6 AC scores 369,831 points in the Geekbench OpenCL test, placing it in the 100th percentile of all GPUs in the database.

Q: Does the NVIDIA Rubin GPU have any benchmark scores?

A: No. The Rubin GPU has an empty benchmark list, an average score of 0, and no nearest rivals recorded.

Q: How does the B300 SXM6 AC compare to the NVIDIA B200?

A: The B300 SXM6 AC is 7% ahead of the B200, which has an average score of 345,482 points.

Q: What is the memory bandwidth difference between the two parts?

A: The B300 SXM6 AC has 8.19 TB/s of HBM3e bandwidth over an 8192-bit bus. The Rubin GPU has 22.1 TB/s of HBM4 bandwidth over a 16384-bit bus.

Q: Which GPU has a higher FP32 throughput?

A: The Rubin GPU delivers 130.0 TFLOPS of FP32, while the B300 SXM6 AC delivers 76.99 TFLOPS, a difference of 68.8%.

Q: What is the TDP of each accelerator?

A: The B300 SXM6 AC has a TDP of 1100 W with a suggested PSU of 1500 W. The Rubin GPU has a TDP of 2300 W with a suggested PSU of 2700 W.

Where Each One Wins

The B300 SXM6 AC wins on verified performance and power efficiency. Its benchmark score of 369,831 is the highest recorded in the database, and its 1100 W TDP is less than half of the Rubin GPU's 2300 W. For deployments where measured output matters and power density is a constraint, the B300 SXM6 AC is the data-backed choice. It also wins on readiness: it has a recorded release date of September 10, 2025, while the Rubin GPU's release date is December 31, 2025, indicating later availability.

The Rubin GPU wins on architectural headroom. Its 3 nm process, 336,000 million transistors, and 230.8M transistors per mm² density outclass the B300 SXM6 AC's 5 nm process and 127.8M per mm² density. Memory bandwidth is decisively in the Rubin GPU's favor at 22.1 TB/s versus 8.19 TB/s, which matters for large-scale model training and inference. Compute throughput is also higher: 130.0 TFLOPS FP32 and 260.0 TFLOPS FP16 versus 76.99 TFLOPS in both for the B300 SXM6 AC. The Rubin GPU also has more shading units (28,672 vs 18,944), more TMUs (896 vs 592), and more tensor cores (896 vs 592).

In specific workload terms, the B300 SXM6 AC is the safer pick for immediate deployment with known performance. The Rubin GPU is the pick for workloads that can exploit its 2:1 FP16 ratio and doubled memory bandwidth, provided the 2300 W power budget is acceptable. The data does not support a recommendation for the Rubin GPU on measured grounds, but its specification sheet wins on every major compute and memory metric except ROP count, which is tied at 24.