AMD Radeon HD 6950 vs NVIDIA Quadro K4000 Comparison

Head-to-Head Benchmarks

The single available head-to-head comparison is the Geekbench OpenCL test, and it tells a surprisingly one-sided story. The NVIDIA Quadro K4000 scores 6816, while the AMD Radeon HD 6950 trails with 6210. That is a delta of -8.9% for the AMD card, meaning NVIDIA wins this benchmark by nearly nine percentage points. Given that the HD 6950 carries a 200W TDP and the K4000 operates at just 80W, this result is striking — the lower-power, smaller-die card delivers the higher compute score.

Looking at the broader context from each card’s nearest rivals, the HD 6950’s 6210 sits within a very tight cluster. It is only 0.2% behind the AMD FirePro W600 (6223), 0.9% behind the NVIDIA GeForce RTX 4070 Ti SUPER AD102 (6270), and 1.1% behind the NVIDIA Quadro K620 (6282). The K4000’s 6816, by contrast, is a full 9.8% above its closest listed rival, the NVIDIA Quadro K4000M (5986, delta -0.1%). In other words, the K4000 is not merely edging out the HD 6950; it is pulling away from an entire field of similarly-scored cards.

The win tally reinforces the asymmetry: the K4000 claims 1 win, the HD 6950 claims 0. However, that single OpenCL result does not capture everything. The K4000 also posts scores in Vulkan (6964) and Metal (4166), while the HD 6950 has no corresponding entries in those APIs. The Vulkan figure is particularly notable — it is higher than the OpenCL score, suggesting the Kepler architecture scales well with modern compute APIs. The Metal score is much lower, which may hint at driver maturity or architectural preference for certain workloads.

What does this imply for the head-to-head? The OpenCL delta is decisive in raw compute terms. But the HD 6950’s higher pixel rate (25.60 GPixel/s vs 12.96 GPixel/s) and texture rate (70.40 GTexel/s vs 51.84 GTexel/s) suggest that in rasterization-heavy tasks, the AMD card could still hold an advantage — the benchmark data simply does not measure that directly. The data available says the K4000 wins the compute contest, but the pixel and texture throughput numbers imply the HD 6950 is not obsolete for graphics work.

FAQ

Q: Which card scores higher in the Geekbench OpenCL test?

A: The NVIDIA Quadro K4000 scores 6816, which is 8.9% higher than the AMD Radeon HD 6950’s 6210. The K4000 wins the only direct head-to-head benchmark available.

Q: How does the HD 6950 compare to its nearest rivals?

A: The HD 6950’s 6210 score is within 1.1% of three rivals: the AMD FirePro W600 (6223, -0.2%), the NVIDIA GeForce RTX 4070 Ti SUPER AD102 (6270, -0.9%), and the NVIDIA Quadro K620 (6282, -1.1%). It is effectively tied with them in compute performance.

Q: Does the Quadro K4000 support modern graphics APIs?

A: Yes. The K4000 lists DirectX 12 (11_0), OpenGL 4.6, and Vulkan 1.2.175. The HD 6950 supports DirectX 11.2 (11_0) and OpenGL 4.4, with no Vulkan support listed.

Q: What is the memory configuration difference?

A: The HD 6950 has 2 GB of GDDR5 on a 256-bit bus, yielding 160.0 GB/s bandwidth. The K4000 has 3 GB of GDDR5 on a 192-bit bus, yielding 134.8 GB/s bandwidth. The AMD card has higher bandwidth, but the NVIDIA card has more capacity.

Q: Which card has a smaller physical footprint?

A: The K4000 is a single-slot card measuring 241 mm in length and 111 mm in height. The HD 6950 is a dual-slot card measuring 286 mm in length and 126 mm in height. The K4000 is shorter and narrower.

Q: What do the percentile rankings say about each card?

A: The HD 6950 sits in the 36th percentile of all GPUs, while the K4000 sits in the 34th percentile. Despite the K4000 winning the head-to-head, both cards are in the same lower-mid range of overall GPU performance.

Architecture Differences

The two cards come from fundamentally different design philosophies. The AMD Radeon HD 6950 uses the Cayman chip on the TeraScale 3 architecture, fabricated on TSMC’s 40 nm process. It packs 2,640 million transistors onto a 389 mm² die, giving a transistor density of 6.8M per mm². The NVIDIA Quadro K4000 uses the GK106 chip on the Kepler architecture, built on TSMC’s 28 nm process. It contains 2,540 million transistors on a much smaller 221 mm² die, achieving 11.5M transistors per mm² — nearly double the density of the AMD chip.

That density gap explains a lot. The K4000 fits roughly the same transistor count into nearly half the silicon area, which is a generational leap in process technology. The HD 6950’s larger die does not translate into more compute units per transistor; the AMD card has 1408 shading units, 88 TMUs, and 32 ROPs, while the K4000 has 768 shading units, 64 TMUs, and 24 ROPs. The AMD card has nearly twice the shading units, yet it loses in OpenCL — a sign that Kepler’s compute efficiency per core is substantially higher.

TeraScale 3 is a VLIW-based architecture, whereas Kepler is a scalar design. That difference matters for how work is scheduled and executed. VLIW relies on the compiler packing multiple operations into wide instructions, which can be inefficient if code does not align well. Kepler’s scalar cores handle divergent workloads more gracefully, which likely explains the OpenCL result. The HD 6950’s raw throughput numbers — 2.253 TFLOPS FP32 versus 1,244.2 GFLOPS for the K4000 — suggest the AMD card should win compute, but the benchmark says otherwise. The data implies Kepler extracts more useful work per FLOP.

Both cards are end-of-life products. The HD 6950 belongs to the Northern Islands generation (HD 6900 series), with the Evergreen series as its predecessor and Southern Islands as its successor. The K4000 belongs to the Quadro Kepler (Kx000) generation, with Quadro Fermi as its predecessor and Quadro Maxwell as its successor. Neither supports hardware ray tracing or tensor cores — those fields are null for both.

Specification Differences

The most obvious difference is in power consumption. The HD 6950 has a 200W TDP and requires two 6-pin power connectors plus a 550W suggested PSU. The K4000 has an 80W TDP, needs only one 6-pin connector, and suggests a 250W PSU. That is a 120W gap, making the K4000 far more power-efficient in absolute terms.

Memory configuration differs in both size and bus width. The HD 6950 offers 2 GB with a 256-bit bus, while the K4000 offers 3 GB with a 192-bit bus. Bandwidth follows: 160.0 GB/s for AMD versus 134.8 GB/s for NVIDIA. The memory clock also differs — the HD 6950 runs at 1250 MHz (5 Gbps effective), while the K4000 runs at 1404 MHz (5.6 Gbps effective). The K4000’s faster memory clock partially compensates for its narrower bus.

Physical dimensions set them apart. The HD 6950 is 286 mm long, 126 mm high, and 42 mm wide, occupying two slots. The K4000 is 241 mm long and 111 mm high, occupying one slot with no width specified. This makes the K4000 substantially easier to fit in compact chassis.

Display outputs differ by vendor philosophy. The HD 6950 has 2x DVI, 1x HDMI 1.4a, and 2x mini-DisplayPort 1.2. The K4000 has 1x DVI and 2x DisplayPort 1.2. The AMD card offers more total outputs, while the NVIDIA card sticks to a simpler configuration.

API support shows a generational gap. The HD 6950 supports DirectX 11.2 (11_0) and OpenGL 4.4, with no Vulkan. The K4000 supports DirectX 12 (11_0), OpenGL 4.6, and Vulkan 1.2.175. The K4000’s Vulkan support is particularly significant for modern workloads, while the HD 6950 is locked out of that API entirely.

Release dates differ by over two years: the HD 6950 launched on 2010-12-13, while the K4000 launched on 2013-02-28. The launch MSRP also differs dramatically — 299 USD for the HD 6950 versus 1,269 USD for the K4000.

Where Each One Wins

The K4000 wins the compute benchmark decisively. Its 6816 OpenCL score versus 6210 for the HD 6950 means the NVIDIA card is the better choice for any workload that relies on OpenCL compute — think scientific simulations, rendering, or data processing. The K4000 also has Vulkan support with a score of 6964, which is its best result across all benchmarks. That makes the K4000 the pick for modern compute APIs that the HD 6950 cannot even access.

The HD 6950, despite losing the compute test, has structural advantages in graphics throughput. Its pixel rate of 25.60 GPixel/s is nearly double the K4000’s 12.96 GPixel/s, and its texture rate of 70.40 GTexel/s exceeds the K4000’s 51.84 GTexel/s. For fill-rate-bound scenarios — high-resolution texturing, multi-sampled anti-aliasing, or heavy overdraw — the HD 6950 should outperform based on these raw figures. The benchmark does not test this directly, but the specifications point that way.

The HD 6950 also wins on memory bandwidth. At 160.0 GB/s versus 134.8 GB/s, the AMD card moves data 18.7% faster, which can matter for large textures or framebuffer operations. Its 256-bit bus is a wider pipe, even if the K4000’s memory runs at a higher clock speed.

The K4000 wins on power efficiency and physical integration. An 80W TDP versus 200W means the K4000 draws 60% less power, requires a smaller PSU, and needs only a single slot. For multi-GPU workstations or dense server environments, that is a decisive practical advantage. The K4000’s shorter length (241 mm vs 286 mm) and lower height (111 mm vs 126 mm) make it easier to install in constrained cases.

The Verdict

The data points to a clear split: the Quadro K4000 is the better compute card, while the Radeon HD 6950 has theoretical graphics throughput advantages that the benchmark does not measure. If the workload is OpenCL-heavy, the K4000 wins outright — its 6816 score is 8.9% above the HD 6950’s 6210, and it does so at 80W versus 200W. The K4000’s Vulkan support (score 6964) and DirectX 12 compatibility further extend its relevance for modern software.

The HD 6950’s case rests on its fill-rate and bandwidth numbers. With 25.60 GPixel/s and 70.40 GTexel/s, it is built for raw rasterization throughput. Its 160.0 GB/s bandwidth and 256-bit bus give it a memory pipeline that the K4000 cannot match. For legacy DirectX 11 workloads or custom rendering pipelines that are fill-rate-bound, the HD 6950 may still hold an edge — but this is inference from specifications, not from a benchmark win.

The percentile rankings complicate the picture. The HD 6950 sits at the 36th percentile of all GPUs, while the K4000 sits at the 34th percentile. Despite the K4000 winning the head-to-head, the overall database places the HD 6950 slightly higher relative to the entire GPU landscape. That suggests the HD 6950’s strengths in non-compute areas are reflected in its aggregate standing.

Who should pick which? The K4000 is the choice for users prioritizing compute efficiency, modern API support, low power draw, and compact physical design. Its single-slot form factor and 80W TDP make it viable in environments where the HD 6950 would be impractical. The HD 6950 is the choice for users who need maximum fill rate and bandwidth in a legacy DirectX 11 context, and who can tolerate a 200W power draw and dual-slot footprint. The launch MSRP difference is stark — 299 USD for the HD 6950 versus 1,269 USD for the K4000 — but both are end-of-life products, so those figures are historical reference points rather than current purchase guidance. The benchmark evidence favors the K4000 for compute, and the specification evidence favors the HD 6950 for raw graphics throughput. Choose accordingly.