NVIDIA B300 vs NVIDIA Rubin GPU Comparison

# FAQ

Q: What are the core specifications of the NVIDIA B300 and NVIDIA Rubin GPU?

A: The NVIDIA B300 is built on the Blackwell Ultra architecture with the GB110 chip, while the NVIDIA Rubin GPU uses the Rubin architecture with the GR100 chip. The B300 has 18,944 shading units, 592 TMUs, and 592 tensor cores, whereas the Rubin GPU has 28,672 shading units, 896 TMUs, and 896 tensor cores.

Q: How do the memory configurations compare between these two GPUs?

A: The B300 features 144 GB of HBM3e memory with a 4096-bit bus and 4.10 TB/s bandwidth. The Rubin GPU doubles this to 288 GB of HBM4 memory, using a 16384-bit bus and delivering 22.1 TB/s bandwidth, which is over five times the memory bandwidth of the B300.

Q: What are the transistor counts and manufacturing processes for each chip?

A: The B300's GB110 chip contains 104,000 million transistors and is fabricated on TSMC's 5 nm process. The Rubin GPU's GR100 chip packs 336,000 million transistors on a 3 nm process, with a die size of 1456 mm² and a transistor density of 230.8M per mm².

Q: Which GPU has the higher boost clock speed?

A: The NVIDIA Rubin GPU has a boost clock of 2267 MHz, compared to the B300's boost clock of 2032 MHz. However, the B300 has a much higher base clock at 1665 MHz versus the Rubin GPU's 700 MHz base clock.

Q: What are the power requirements for these server modules?

A: The B300 has a TDP of 1400 W and a suggested PSU of 1800 W. The Rubin GPU is more power-hungry, with a TDP of 2300 W and a suggested PSU of 2700 W.

Q: What is the FP32 and FP16 compute performance for each GPU?

A: The B300 delivers 76.99 TFLOPS FP32 and 1,231.8 TFLOPS FP16 (16:1 ratio). The Rubin GPU provides 130.0 TFLOPS FP32 and 260.0 TFLOPS FP16 (2:1 ratio). While the Rubin GPU has significantly higher FP32 throughput, the B300's FP16 figure is much larger due to the different ratio configuration.

# Architecture Differences

The NVIDIA B300 and NVIDIA Rubin GPU represent two distinct architectural generations from NVIDIA, separated by process technology and design philosophy. The B300 uses the Blackwell Ultra architecture with the GB110 chip, manufactured on TSMC's 5 nm process. In contrast, the Rubin GPU introduces the Rubin architecture with the GR100 chip, built on the more advanced TSMC 3 nm process. This process shrink allows the GR100 to house 336,000 million transistors, more than triple the 104,000 million transistors in the GB110. The Rubin GPU also has a substantial die size of 1456 mm², a figure not provided for the B300, with a transistor density of 230.8M per mm².

Memory architecture differs fundamentally between the two. The B300 uses HBM3e memory, offering 144 GB capacity across a 4096-bit bus. The Rubin GPU steps up to HBM4, doubling capacity to 288 GB and quadrupling the bus width to 16384 bits. This results in a memory bandwidth of 22.1 TB/s for the Rubin GPU, compared to 4.10 TB/s for the B300. The memory clock also differs, with the B300 running at 2000 MHz (8 Gbps effective) and the Rubin GPU at 2695 MHz (10.8 Gbps effective).

The compute resources are scaled up significantly on the Rubin GPU. Shading units increase from 18,944 on the B300 to 28,672 on the Rubin GPU. Texture mapping units go from 592 to 896, and tensor cores from 592 to 896. Both GPUs maintain 24 ROPs, an unusual parity given the other differences. The texture rate on the Rubin GPU reaches 2,031.2 GTexel/s versus 1,202.9 GTexel/s on the B300, while pixel rates are 54.41 GPixel/s and 48.77 GPixel/s respectively.

Clock behavior shows a notable divergence. The B300 has a higher base clock of 1665 MHz, while the Rubin GPU starts at just 700 MHz. Boost clocks are closer, with the B300 at 2032 MHz and the Rubin GPU at 2267 MHz. This suggests the Rubin GPU relies more heavily on boost behavior under load.

The bus interface also advances: the B300 uses PCIe 5.0 x16, while the Rubin GPU adopts PCIe 6.0 x16. Both are SXM modules with no display outputs, reflecting their server-focused design. The Rubin GPU explicitly lists DirectX, OpenGL, and Vulkan as N/A, while the B300 leaves these fields unspecified. Power delivery differs substantially, with the Rubin GPU's 2300 W TDP exceeding the B300's 1400 W, and suggested PSU ratings of 2700 W versus 1800 W.

# Where Each One Wins

The NVIDIA B300 demonstrates strengths in specific workload characteristics, particularly around its FP16 compute capabilities. The B300 delivers 1,231.8 TFLOPS FP16, a figure that dwarfs the Rubin GPU's 260.0 TFLOPS FP16. This 16:1 ratio on the B300 indicates an architecture optimized for certain mixed-precision or tensor-heavy operations where FP16 throughput is paramount. The B300 also has a significantly higher base clock, which may benefit workloads with sustained, predictable compute patterns that do not rely on boost variability.

The NVIDIA Rubin GPU wins decisively in raw FP32 throughput, delivering 130.0 TFLOPS versus the B300's 76.99 TFLOPS. This makes the Rubin GPU the stronger choice for traditional single-precision compute tasks such as scientific simulation, certain rendering pipelines, and general-purpose GPU computing. The Rubin GPU also dominates memory bandwidth at 22.1 TB/s, which is more than five times the B300's 4.10 TB/s. Applications that are memory-bandwidth bound, such as large-scale data processing, deep learning training with massive datasets, or high-resolution inference, would see substantial benefits from the Rubin GPU's memory subsystem.

The Rubin GPU's larger memory capacity of 288 GB versus 144 GB gives it a clear advantage for models and datasets that exceed the B300's memory ceiling. The HBM4 memory type also represents a generational improvement over HBM3e. Texture throughput is another area where the Rubin GPU excels, with 2,031.2 GTexel/s compared to the B300's 1,202.9 GTexel/s, benefiting texturing-heavy workloads.

The B300 wins in power efficiency per FP16 operation, given its much lower 1400 W TDP while delivering substantially higher FP16 throughput. However, the Rubin GPU provides more raw FP32 performance per watt when considering its 2300 W TDP against its 130.0 TFLOPS FP32 output. The B300's smaller transistor count and older process node may also translate to different thermal characteristics, though the database does not provide thermal measurements.

# Specification Differences

The following table highlights the key specification differences between the NVIDIA B300 and NVIDIA Rubin GPU:

| Specification | NVIDIA B300 | NVIDIA Rubin GPU |

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

| Chip | GB110 | GR100 |

| Architecture | Blackwell Ultra | Rubin |

| Process Node | 5 nm | 3 nm |

| Transistors | 104,000 million | 336,000 million |

| Die Size | Not specified | 1456 mm² |

| Transistor Density | Not specified | 230.8M / mm² |

| Base Clock | 1665 MHz | 700 MHz |

| Boost Clock | 2032 MHz | 2267 MHz |

| Memory Clock | 2000 MHz (8 Gbps effective) | 2695 MHz (10.8 Gbps effective) |

| Memory Size | 144 GB | 288 GB |

| Memory Type | HBM3e | HBM4 |

| Memory Bus Width | 4096 bit | 16384 bit |

| Memory Bandwidth | 4.10 TB/s | 22.1 TB/s |

| Shading Units | 18944 | 28672 |

| TMUs | 592 | 896 |

| ROPs | 24 | 24 |

| Tensor Cores | 592 | 896 |

| Pixel Rate | 48.77 GPixel/s | 54.41 GPixel/s |

| Texture Rate | 1,202.9 GTexel/s | 2,031.2 GTexel/s |

| FP32 Performance | 76.99 TFLOPS | 130.0 TFLOPS |

| FP16 Performance | 1,231.8 TFLOPS (16:1) | 260.0 TFLOPS (2:1) |

| TDP | 1400 W | 2300 W |

| Suggested PSU | 1800 W | 2700 W |

| Bus Interface | PCIe 5.0 x16 | PCIe 6.0 x16 |

| Release Date | 2025-09-10 | 2025-12-31 |

| Predecessor | Server Hopper | Server Blackwell |

| Successor | Server Rubin | Not specified |

| DirectX / OpenGL / Vulkan | Not specified | N/A |

Both GPUs share the SXM Module slot width, have no display outputs, and are produced by NVIDIA with Active production status. Neither has a launch MSRP recorded in the database.

# Head-to-Head Benchmarks

The database records no direct head-to-head benchmark results between the NVIDIA B300 and NVIDIA Rubin GPU. Both devices show zero benchmark scores, an average benchmark score of 0, and a percentile rank of 50 against all GPUs. This means the comparison must rely entirely on the specification-level data provided.

The most significant performance gap appears in memory bandwidth, where the Rubin GPU's 22.1 TB/s represents a 5.39 times advantage over the B300's 4.10 TB/s. In practical terms, this suggests the Rubin GPU can move data through its memory subsystem at a rate that the B300 cannot approach, which would be decisive for any memory-bound workload.

FP32 compute shows the Rubin GPU ahead by 53.0 TFLOPS, or approximately 68.8% higher than the B300's 76.99 TFLOPS. This is a substantial margin for single-precision workloads. The texture rate also favors the Rubin GPU by 828.3 GTexel/s, a 68.9% improvement. Pixel rates are closer, with the Rubin GPU at 54.41 GPixel/s versus 48.77 GPixel/s, a difference of 5.64 GPixel/s or about 11.6%.

The FP16 comparison reverses the trend. The B300's 1,231.8 TFLOPS FP16 is 4.74 times the Rubin GPU's 260.0 TFLOPS. This reflects the different FP16 ratios: the B300 uses a 16:1 ratio while the Rubin GPU uses a 2:1 ratio. The B300's FP16 configuration appears designed for extremely high throughput in certain tensor or mixed-precision operations, while the Rubin GPU's closer ratio suggests more balanced FP16 and FP32 performance.

Clock speeds present a mixed picture. The B300's base clock of 1665 MHz is 965 MHz higher than the Rubin GPU's 700 MHz base clock. However, the Rubin GPU's boost clock of 2267 MHz exceeds the B300's 2032 MHz by 235 MHz. The B300's higher base clock could indicate better sustained performance in thermal or power-constrained scenarios, while the Rubin GPU's higher boost clock shows greater peak capability.

Memory capacity and type favor the Rubin GPU decisively. At 288 GB with HBM4, it doubles the B300's 144 GB HBM3e. The bus width difference is even more dramatic, with the Rubin GPU using a 16384-bit bus versus 4096 bits, a fourfold increase. These specifications position the Rubin GPU for much larger working sets and higher memory throughput.

The transistor count difference is substantial. The Rubin GPU's GR100 chip contains 336,000 million transistors, 232,000 million more than the B300's GB110. Combined with the 3 nm process node and 1456 mm² die size, this indicates a much more complex and capable processor. The B300's transistor density is not recorded, but the Rubin GPU's 230.8M per mm² density reflects the advanced manufacturing process.

# The Verdict

The data presents two distinct design philosophies from NVIDIA. The NVIDIA B300, released on 2025-09-10, uses the Blackwell Ultra architecture with a 5 nm process and 104,000 million transistors. Its defining characteristic is the FP16 performance of 1,231.8 TFLOPS at a 16:1 ratio, which vastly exceeds the Rubin GPU's FP16 output. For workloads that leverage this specific FP16 capability, the B300 appears purpose-built. The B300 also has a higher base clock of 1665 MHz and a lower TDP of 1400 W with a suggested PSU of 1800 W.

The NVIDIA Rubin GPU, released on 2025-12-31, represents the next generation with the Rubin architecture, 3 nm process, and 336,000 million transistors. Its strengths lie in FP32 compute at 130.0 TFLOPS, memory bandwidth at 22.1 TB/s, memory capacity at 288 GB, and texture throughput at 2,031.2 GTexel/s. The PCIe 6.0 x16 interface and HBM4 memory type further distinguish it as the more advanced platform.

Users with FP16-dominated workloads, such as certain AI training or inference scenarios that rely on the 16:1 ratio configuration, would find the B300's specifications more aligned with their needs. The B300's lower power draw and higher base clock may also suit environments where power delivery or sustained clock behavior is constrained.

Users requiring maximum FP32 throughput, massive memory bandwidth, or the largest memory capacity would select the Rubin GPU. Its 288 GB HBM4 memory and 22.1 TB/s bandwidth create a substantial performance envelope for data-intensive applications. The Rubin GPU also delivers higher pixel and texture rates, making it stronger for graphics-related compute tasks.

The absence of recorded benchmark scores and the equal 50th percentile ranking mean the database does not yet validate either GPU's real-world performance. The specification analysis, however, clearly shows the Rubin GPU as the more powerful and feature-rich device across most metrics, with the B300 holding a specific advantage in FP16 throughput and base clock speed. The choice between them depends entirely on whether the workload prioritizes the B300's FP16 specialization or the Rubin GPU's broader compute and memory advantages.