AMD Radeon HD 6950 vs AMD Radeon RX 6400 Comparison

The AMD Radeon HD 6950 and the AMD Radeon RX 6400 represent two distinct eras of graphics technology, separated by over a decade of architectural evolution. The data available for direct comparison is limited to a single OpenCL workload, yet that result is decisive. In the Geekbench OpenCL test, the RX 6400 scores 32,011 points, which is a staggering 80.6% higher than the HD 6950’s 6,210 points. This is not a marginal victory; it is a generational gap made visible. The HD 6950’s average benchmark score of 6,210 places it at the 36th percentile of all GPUs, while the RX 6400’s average of 6,001 places it at the 35th percentile, despite the RX 6400’s superior raw score in this specific test. The disparity in the head-to-head result dwarfs the differences seen in their nearest rivals, where the HD 6950 sits within 1.1% of cards like the NVIDIA Quadro K620 and the RX 6400 is effectively tied with the NVIDIA GeForce GTX 770M.

Head-to-Head Benchmarks

The only direct head-to-head benchmark available is Geekbench OpenCL, and it paints a clear picture of performance hierarchy. The AMD Radeon RX 6400 delivers a score of 32,011, while the AMD Radeon HD 6950 manages only 6,210. The delta of -80.6% indicates that the HD 6950’s score is roughly one-fifth that of the newer card. This is a massive gap, far exceeding the small margins seen when comparing each card to its own nearest rivals. For context, the HD 6950’s closest competitor, the AMD FirePro W600, scores 6,223, a mere 0.2% difference, and even the NVIDIA GeForce RTX 5070 Ti SUPER, with a score of 6,270, is only 0.9% ahead. The RX 6400, on the other hand, is surrounded by very different company; its nearest rival, the NVIDIA GeForce GTX 770M, scores 6,000, which is essentially a statistical tie with a 0.0% delta. This suggests that while the HD 6950 competes in a low-score bracket, the RX 6400’s OpenCL result is an outlier compared to its other benchmark scores, which average much lower, pulling its overall percentile down to 35.

The data implies that the RX 6400’s architecture is fundamentally more efficient at compute tasks that OpenCL measures. The HD 6950, with its older TeraScale 3 design, simply cannot keep pace in this synthetic workload. While the RX 6400 wins the only head-to-head test, it is important to note that its other benchmarks, like Passmark G3D at 7,673 and Passmark G2D at 722, show a more modest performance profile. The HD 6950 has no other benchmark results in the fact pack, so we cannot compare 3DMark or Passmark scores directly. The single OpenCL result, however, is so lopsided that it defines the performance relationship between these two cards, suggesting that any modern workload would favor the RX 6400 by a wide margin.

Where Each One Wins

Based strictly on the available data, the AMD Radeon RX 6400 is the clear winner in the only benchmark where both cards appear. This single victory in Geekbench OpenCL indicates that the RX 6400 holds a decisive advantage in general-purpose GPU compute tasks, likely due to its modern RDNA 2.0 architecture and significantly higher clock speeds. The HD 6950, meanwhile, has no benchmark wins in this comparison. Its only score, 6,210 in Geekbench OpenCL, is its sole data point, and it falls far short of the RX 6400’s 32,011. Therefore, in any scenario that relies on OpenCL performance, the RX 6400 is the superior choice.

However, the absence of other common benchmarks like 3DMark or Passmark for the HD 6950 means we cannot assess where the older card might have excelled. The RX 6400’s Passmark scores show a mixed bag: it scores 93 in DirectX 9, 70 in DirectX 11, and 54 in DirectX 10, but only 30 in DirectX 12. This suggests that while it is strong in legacy APIs, its performance in modern DirectX 12 titles may not be as dominant, despite its architectural support for DirectX 12 Ultimate. The HD 6950, with its DirectX 11.2 support, would likely struggle in DirectX 12 workloads, but the data does not provide a direct comparison. The fact pack shows the RX 6400 has 768 shading units, 48 texture mapping units, and 32 ROPs, while the HD 6950 has 1,408 shading units, 88 TMUs, and 32 ROPs. This means the HD 6950 has more raw shader hardware, but the RX 6400’s higher clock speeds and newer instruction set apparently more than compensate, at least in OpenCL.

Architecture Differences

The architectural gap between these two GPUs is profound and explains the benchmark disparity. The AMD Radeon HD 6950 is built on the TeraScale 3 architecture, using the Cayman chip manufactured on a 40 nm process at TSMC. It packs 2,640 million transistors into a large 389 mm² die, resulting in a transistor density of 6.8 million per mm². In contrast, the AMD Radeon RX 6400 uses the RDNA 2.0 architecture with the Navi 24 chip, produced on a much more advanced 6 nm process, also at TSMC. This newer node allows it to fit 5,400 million transistors into a much smaller 107 mm² die, achieving a density of 50.5 million per mm². The shift from 40 nm to 6 nm is a key factor in the RX 6400’s efficiency, enabling higher clock speeds and lower power consumption.

Clock speeds further illustrate the generational leap. The HD 6950 has no base or boost clock listed, but its memory runs at 1250 MHz, or 5 Gbps effective. The RX 6400, however, has a base clock of 1923 MHz, a game clock of 2039 MHz, and a boost clock of 2321 MHz, with memory running at 2000 MHz, or 16 Gbps effective. This massive clock advantage directly translates to the RX 6400’s higher pixel rate of 74.27 GPixel/s and texture rate of 111.4 GTexel/s, compared to the HD 6950’s 25.60 GPixel/s and 70.40 GTexel/s. Floating-point performance tells a similar story: the RX 6400 delivers 3.565 TFLOPS of FP32 compute, while the HD 6950 manages 2.253 TFLOPS. The RX 6400 also supports FP16 at 7.130 TFLOPS, a feature the HD 6950 lacks entirely.

Memory subsystems also differ significantly. The HD 6950 uses 2 GB of GDDR5 memory on a 256-bit bus, providing 160.0 GB/s of bandwidth. The RX 6400 uses 4 GB of GDDR6 memory on a much narrower 64-bit bus, yielding 128.0 GB/s of bandwidth. Despite the narrower bus, the faster GDDR6 memory keeps bandwidth competitive, though the HD 6950 actually has higher theoretical bandwidth. The RX 6400 also introduces hardware ray tracing cores, with 12 RT cores, a feature absent from the older card. API support is another differentiator: the RX 6400 supports DirectX 12 Ultimate, OpenGL 4.6, and Vulkan 1.4, while the HD 6950 is limited to DirectX 11.2, OpenGL 4.4, and no Vulkan support. This means the RX 6400 is future-proofed for modern games and applications, while the HD 6950 is stuck in the past.

The Verdict

The data overwhelmingly favors the AMD Radeon RX 6400 for anyone seeking modern performance. Its 80.6% lead in OpenCL benchmarks is a definitive statement of its compute superiority. The RX 6400 also offers modern features like ray tracing support, Vulkan 1.4, and DirectX 12 Ultimate, which are essential for current software. Its power efficiency is remarkable, with a TDP of 53 W compared to the HD 6950’s 200 W, and it requires no external power connectors, whereas the HD 6950 needs two 6-pin connectors and a 550 W power supply. The RX 6400 is also a single-slot card, while the HD 6950 is dual-slot, making the newer card far easier to integrate into compact systems.

The HD 6950, however, is not without merit in a historical context. It has a higher memory bandwidth of 160.0 GB/s and more shading units (1,408 vs. 768), which could theoretically benefit certain legacy workloads that are not well-optimized for newer architectures. Its 2 GB of VRAM, while small by today’s standards, was substantial for its time. The HD 6950’s launch MSRP was 299 USD, while the RX 6400’s was 159 USD, but the price comparison is moot given the performance gap. For any practical purpose, the RX 6400 is the better choice, offering more than five times the OpenCL performance, modern API support, and drastically lower power requirements. The HD 6950’s only advantage lies in its higher bandwidth and raw shader count, which do not translate into real-world wins in the available data. The verdict is clear: the RX 6400 is the superior GPU for nearly all use cases, and the HD 6950 should be considered a relic of a bygone era.

FAQ

Q: Which GPU has a higher Geekbench OpenCL score?

A: The AMD Radeon RX 6400 scores 32,011, which is 80.6% higher than the AMD Radeon HD 6950’s score of 6,210.

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

A: The RX 6400 has a transistor density of 50.5 million per mm², while the HD 6950 has a density of 6.8 million per mm².

Q: Does the HD 6950 support ray tracing?

A: No, the HD 6950 has no ray tracing cores, while the RX 6400 includes 12 RT cores.

Q: What is the memory bandwidth of each GPU?

A: The HD 6950 has a memory bandwidth of 160.0 GB/s, which is higher than the RX 6400’s 128.0 GB/s.

Q: Which card has a lower power consumption?

A: The RX 6400 has a TDP of 53 W and requires no power connectors, whereas the HD 6950 has a TDP of 200 W and needs two 6-pin connectors.

Q: What API support does the HD 6950 lack compared to the RX 6400?

A: The HD 6950 lacks Vulkan support and only supports DirectX 11.2, while the RX 6400 supports Vulkan 1.4 and DirectX 12 Ultimate.

Specification Differences

| Specification | AMD Radeon HD 6950 | AMD Radeon RX 6400 |

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

| Architecture | TeraScale 3 | RDNA 2.0 |

| Process Node | 40 nm | 6 nm |

| Transistors | 2,640 million | 5,400 million |

| Die Size | 389 mm² | 107 mm² |

| Transistor Density | 6.8M / mm² | 50.5M / mm² |

| Base Clock | Not listed | 1923 MHz |

| Boost Clock | Not listed | 2321 MHz |

| Game Clock | Not listed | 2039 MHz |

| Memory Clock | 1250 MHz (5 Gbps effective) | 2000 MHz (16 Gbps effective) |

| Memory Size | 2 GB | 4 GB |

| Memory Type | GDDR5 | GDDR6 |

| Memory Bus Width | 256 bit | 64 bit |

| Memory Bandwidth | 160.0 GB/s | 128.0 GB/s |

| Shading Units | 1408 | 768 |

| TMUs | 88 | 48 |

| ROPs | 32 | 32 |

| RT Cores | None | 12 |

| Pixel Rate | 25.60 GPixel/s | 74.27 GPixel/s |

| Texture Rate | 70.40 GTexel/s | 111.4 GTexel/s |

| FP32 Performance | 2.253 TFLOPS | 3.565 TFLOPS |

| FP16 Performance | Not listed | 7.130 TFLOPS (2:1) |

| TDP | 200 W | 53 W |

| Slot Width | Dual-slot | Single-slot |

| Power Connectors | 2x 6-pin | None |

| Suggested PSU | 550 W | 250 W |

| Bus Interface | PCIe 2.0 x16 | PCIe 4.0 x4 |

| Display Outputs | 2x DVI, 1x HDMI 1.4a, 2x mini-DisplayPort 1.2 | 1x HDMI 2.1, 1x DisplayPort 1.4a |

| DirectX Support | 11.2 (11_0) | 12 Ultimate (12_2) |

| OpenGL Support | 4.4 | 4.6 |

| Vulkan Support | Not listed | 1.4 |

| Launch MSRP | 299 USD | 159 USD |