GPU Comparison

The NVIDIA RTX A400 and NVIDIA Quadro K4000 represent two distinct eras of workstation graphics. The data shows a generational gap that is most clearly quantified in the head-to-head benchmark results, where the newer Ampere-based card holds a decisive advantage in every available test.

Head-to-Head Benchmarks

The most dramatic separation occurs in the Geekbench OpenCL test. The RTX A400 scores 22,844 points, while the Quadro K4000 manages 6,816. This translates to a 235.2% advantage for the A400, a more than threefold increase in raw compute throughput. This is not a marginal improvement; it is a fundamental shift in processing capability that directly impacts any GPU-compute workload.

The Geekbench Vulkan results tell a similar story. The RTX A400 posts 22,237 points versus the K4000's 6,964, a 219.3% lead. Vulkan is a modern API, and the A400's support for version 1.4 versus the K4000's 1.2.175 explains part of this gap. The newer architecture is designed to leverage the API's low-level overhead more efficiently, resulting in a massive performance uplift in this particular test.

These two wins are the only head-to-head comparisons available, and the RTX A400 wins both. The Quadro K4000 does not secure a single victory in the data provided. Looking at the broader aggregate, the A400's average benchmark score is 6,078, while the K4000's is 5,982. This places them at the 35th and 34th percentile of all GPUs, respectively. While the A400 holds a slight edge in the aggregate, the delta is small (1.6%), which highlights that the K4000's performance is not entirely obsolete in older, less parallel workloads. However, in the modern, compute-heavy tests that matter most for current software, the A400 is in a different class.

Architecture Differences

The foundational difference lies in the manufacturing process and chip design. The RTX A400 is built on Ampere architecture using an 8 nm process at Samsung, packing 8,700 million transistors onto a 200 mm² die. The Quadro K4000 uses the older Kepler architecture on a 28 nm process at TSMC, with only 2,540 million transistors on a 221 mm² die. The A400's transistor density is 43.5M / mm² compared to the K4000's 11.5M / mm², a clear indicator of the efficiency gains from the newer node.

Memory technology and configuration also differ significantly. The A400 uses 4 GB of GDDR6 on a 64-bit bus, delivering 96.00 GB/s of bandwidth. The K4000 uses 3 GB of GDDR5 on a 192-bit bus, providing 134.8 GB/s of bandwidth. The K4000 actually has a wider memory bus and higher raw bandwidth, which can benefit certain memory-bound tasks, but the A400's newer GDDR6 memory runs at 1500 MHz (12 Gbps effective) versus the K4000's 1404 MHz (5.6 Gbps effective). The A400's advantage in compute is not mirrored in memory throughput, where the K4000's wider bus gives it a 40.4% bandwidth advantage.

The compute core configurations are starkly different. Both cards have 768 shading units, but the A400 has 24 TMUs and 16 ROPs, while the K4000 has 64 TMUs and 24 ROPs. Despite fewer texture units, the A400 achieves a 42.29 GTexel/s texture rate versus the K4000's 51.84 GTexel/s, and a 28.19 GPixel/s pixel rate versus 12.96 GPixel/s. The A400's higher clocks, 1417 MHz base and 1762 MHz boost, drive its superior pixel throughput. The K4000's missing base and boost clock data suggests it is a legacy product without modern boost behavior. The A400 also introduces dedicated 6 RT cores and 24 tensor cores, features entirely absent from the Kepler-based K4000. This is a fundamental capability difference, enabling hardware-accelerated ray tracing and AI workloads on the A400 that the K4000 cannot perform.

Where Each One Wins

The RTX A400 wins in every modern compute scenario. Its 2.706 TFLOPS of FP32 performance dwarfs the K4000's 1,244.2 GFLOPS, making it the clear choice for general-purpose GPU compute, OpenCL-based rendering, and Vulkan-accelerated applications. The A400's support for DirectX 12 Ultimate (12_2) and Vulkan 1.4 ensures compatibility with the latest graphics features, while the K4000 is limited to DirectX 12 (11_0) and Vulkan 1.2.175. The A400's FP16 performance matches its FP32 at 2.706 TFLOPS (1:1), a feature the K4000 lacks entirely, which is crucial for AI inference and machine learning tasks that leverage the tensor cores.

The Quadro K4000 has a few areas where its older design is not at a disadvantage. Its 134.8 GB/s memory bandwidth is superior to the A400's 96.00 GB/s, which could make it faster in specific, memory-heavy workloads that do not scale with compute throughput. Its 64 TMUs and 24 ROPs are also higher than the A400's, though the A400's higher clock speeds mitigate this in practice. The K4000's 192-bit bus is a legacy design, but it provides a data path that is 50% wider than the A400's 64-bit bus. For a niche set of legacy applications that are sensitive to memory bandwidth rather than raw compute, the K4000 might still hold a slight edge. However, this is a narrow advantage in a fast-shrinking pool of software. The K4000's 1x DVI and 2x DisplayPort 1.2 outputs are older standards compared to the A400's 4x mini-DisplayPort 1.4a, which supports higher resolutions and refresh rates.

FAQ

Q: How much faster is the RTX A400 in OpenCL compared to the Quadro K4000?

A: The RTX A400 scores 22,844 in Geekbench OpenCL, which is 235.2% higher than the K4000's score of 6,816.

Q: Does the Quadro K4000 have any performance advantage over the RTX A400?

A: Yes, in memory bandwidth. The K4000 provides 134.8 GB/s on a 192-bit bus, whereas the A400 provides 96.00 GB/s on a 64-bit bus.

Q: What is the transistor density difference between the two cards?

A: The RTX A400 has a density of 43.5M / mm², while the Quadro K4000 has a density of 11.5M / mm², reflecting the newer 8 nm process versus the older 28 nm process.

Q: Which card has dedicated ray tracing or tensor cores?

A: Only the RTX A400 has them, with 6 RT cores and 24 tensor cores. The Quadro K4000 has none.

Q: What is the memory configuration of each card?

A: The RTX A400 uses 4 GB of GDDR6 memory. The Quadro K4000 uses 3 GB of GDDR5 memory.

Q: Which card has a higher average benchmark score?

A: The RTX A400 has an average benchmark score of 6,078, compared to the Quadro K4000's 5,982.

Specification Differences

| Specification | NVIDIA RTX A400 | NVIDIA Quadro K4000 |

| :--- | :--- | :--- |

| Chip | GA107 | GK106 |

| Architecture | Ampere | Kepler |

| Process Node | 8 nm | 28 nm |

| Transistors | 8,700 million | 2,540 million |

| Die Size | 200 mm² | 221 mm² |

| FP32 Performance | 2.706 TFLOPS | 1,244.2 GFLOPS |

| FP16 Performance | 2.706 TFLOPS (1:1) | null |

| Memory Size | 4 GB | 3 GB |

| Memory Type | GDDR6 | GDDR5 |

| Memory Bus | 64 bit | 192 bit |

| Memory Bandwidth | 96.00 GB/s | 134.8 GB/s |

| RT Cores | 6 | null |

| Tensor Cores | 24 | null |

| TMUs | 24 | 64 |

| ROPs | 16 | 24 |

| Texture Rate | 42.29 GTexel/s | 51.84 GTexel/s |

| Pixel Rate | 28.19 GPixel/s | 12.96 GPixel/s |

| DirectX Support | 12 Ultimate (12_2) | 12 (11_0) |

| Vulkan Support | 1.4 | 1.2.175 |

| Bus Interface | PCIe 4.0 x8 | PCIe 2.0 x16 |

| Display Outputs | 4x mini-DisplayPort 1.4a | 1x DVI, 2x DisplayPort 1.2 |

| TDP | 50 W | 80 W |

| Power Connectors | None | 1x 6-pin |

| Production Status | Active | End-of-life |

The Verdict

The data points to the NVIDIA RTX A400 as the definitive choice for any modern workstation task. Its 235.2% lead in OpenCL and 219.3% lead in Vulkan are not just wins; they are sweeping victories that reflect a fundamental architectural advantage. The inclusion of RT and tensor cores, coupled with higher FP32 and FP16 performance, makes it the only viable option for current software that leverages these features. Its lower 50 W TDP and lack of power connectors also make it a simpler and more energy-efficient addition to a system.

The Quadro K4000, with its end-of-life status and legacy Kepler architecture, is a product from a different computing era. Its only theoretical edge is its 134.8 GB/s memory bandwidth, which is a niche advantage in specific memory-bound legacy applications. However, this does not compensate for its 1,244.2 GFLOPS FP32 performance, which is less than half of the A400's 2.706 TFLOPS. Its lack of modern API support (no DirectX 12 Ultimate, older Vulkan) and absence of RT and tensor cores make it unsuitable for current professional workloads. The K4000's higher 80 W TDP and requirement for a 6-pin power connector also indicate a less efficient design. For a professional seeking a current, supported, and faster GPU, the RTX A400 is the only rational choice based on the benchmark evidence. The K4000 is a relic that should only be considered for very specific, dated hardware compatibility needs.