AMD Radeon HD 6950 vs NVIDIA GeForce GT 555M Comparison

The NVIDIA GeForce GT 555M and AMD Radeon HD 6950 represent two very different philosophies in GPU design, and their benchmark scores reflect that. The GeForce GT 555M is a mobile part, designed for the constraints of a laptop, while the Radeon HD 6950 is a high-end desktop card built for maximum throughput. The data shows they are surprisingly close in the Geekbench OpenCL test, with the GT 555M edging out a 4.6% victory, but a closer look at their architectures and specifications reveals that this is a comparison of a compact, efficient chip against a massive, power-hungry one.

Where Each One Wins

The use-case split is defined by the environments these cards were built for, rather than by a clear dominance in raw compute. The NVIDIA GeForce GT 555M’s strengths lie in its portability and efficiency. With a thermal design power (TDP) of only 35 W, it is designed to fit into a laptop chassis where heat and power draw are critical constraints. Its "Portable Device Dependent" display outputs confirm its purpose is to serve a mobile screen, not a multi-monitor desktop setup. In this context, it wins by simply being a capable GPU that can exist in a laptop, offering a significant step up from integrated graphics.

The AMD Radeon HD 6950, conversely, wins on sheer capability and memory bandwidth. It is a dual-slot desktop card that requires two 6-pin power connectors and a 550 W power supply. Its 2 GB of GDDR5 memory on a 256-bit bus provides 160.0 GB/s of bandwidth, a figure that is over 5.5 times higher than the GT 555M’s 28.80 GB/s. This makes it the clear winner for tasks that are memory-intensive, such as rendering large textures or compute workloads that require large data sets to be moved quickly. It also offers a wider array of display outputs, including 2x DVI, 1x HDMI 1.4a, and 2x mini-DisplayPort 1.2, making it the superior choice for multi-monitor or external display configurations.

In terms of benchmark wins, the data is clear: the GT 555M wins the sole Geekbench OpenCL test. However, this is a narrow victory that requires deeper analysis, as the HD 6950’s massive architectural advantages suggest its lower score is a quirk of the test or driver maturity, not a true representation of its overall performance potential. The GT 555M wins the specific test, but the HD 6950 wins the argument for desktop-grade power.

Architecture Differences

The architectural divide is stark. The NVIDIA GeForce GT 555M is built on the Fermi architecture, using the GF106 chip, while the AMD Radeon HD 6950 uses the TeraScale 3 architecture on the Cayman chip. Both are manufactured by TSMC on the same 40 nm process node, but that is where the similarities end. The GT 555M is a relatively small chip, with a die size of 238 mm² and 1,170 million transistors. The HD 6950 is a monster in comparison, with a die size of 389 mm² and 2,640 million transistors, more than double the count. This leads to a higher transistor density of 6.8M / mm² for the AMD part versus 4.9M / mm² for the NVIDIA part, showing that AMD packed more logic into each square millimeter.

The core configurations are completely different. The GT 555M has 144 shading units, 24 texture mapping units (TMUs), and 16 render output units (ROPs). The HD 6950, on the other hand, has 1408 shading units, 88 TMUs, and 32 ROPs. This is a difference of nearly 10 times the shading units and almost 4 times the TMUs. Consequently, the theoretical pixel and texture rates are far higher on the AMD card: 25.60 GPixel/s and 70.40 GTexel/s versus the NVIDIA’s 3.540 GPixel/s and 14.16 GTexel/s. The FP32 compute performance also reflects this, with the HD 6950 delivering 2.253 TFLOPS compared to the GT 555M’s 339.8 GFLOPS.

Memory architecture is another major divergence. The GT 555M uses 1024 MB of DDR3 memory on a 128-bit bus, while the HD 6950 uses 2 GB of GDDR5 on a 256-bit bus. The effective memory clock speeds also differ, with the HD 6950 running at 5 Gbps effective versus the GT 555M’s 1800 Mbps effective. This combination of wider bus and faster memory gives the HD 6950 its massive bandwidth advantage. The API support is similar, with both supporting DirectX 11_0 and neither supporting Vulkan, but the HD 6950 lists OpenGL 4.4 while the GT 555M lists OpenGL 4.6.

FAQ

Q: Which GPU has a higher average benchmark score?

A: The NVIDIA GeForce GT 555M has a higher average benchmark score of 6493, placing it in the 37th percentile of all GPUs. The AMD Radeon HD 6950 has an average score of 6210, placing it in the 36th percentile.

Q: How significant is the performance difference between the two?

A: In the head-to-head Geekbench OpenCL test, the NVIDIA GeForce GT 555M wins by a delta of 4.6%, scoring 6493 against the AMD’s 6210. This is a narrow margin, suggesting the two are closely matched in this specific workload.

Q: Which card has more memory and bandwidth?

A: The AMD Radeon HD 6950 has significantly more memory and bandwidth. It features 2 GB of GDDR5 memory on a 256-bit bus, resulting in 160.0 GB/s of bandwidth. The NVIDIA GeForce GT 555M has 1024 MB of DDR3 memory on a 128-bit bus, providing only 28.80 GB/s.

Q: What are the power requirements for each card?

A: The NVIDIA GeForce GT 555M is a low-power mobile chip with a TDP of 35 W and no dedicated power connectors, as it is portable device dependent. The AMD Radeon HD 6950 is a desktop card with a 200 W TDP, requiring two 6-pin power connectors and a suggested 550 W power supply.

Q: How do their shading unit counts compare?

A: The AMD Radeon HD 6950 has 1408 shading units, which is vastly more than the 144 shading units found on the NVIDIA GeForce GT 555M. This architectural difference suggests the AMD card is designed for parallel throughput.

Q: Which card is larger physically?

A: The AMD Radeon HD 6950 is a large dual-slot desktop card, measuring 286 mm in length, 126 mm in height, and 42 mm in width. The NVIDIA GeForce GT 555M has no listed dimensions, as it is a chip designed for integration into portable devices.

Specification Differences

The following table highlights the key differences in their specifications.

| Specification | NVIDIA GeForce GT 555M | AMD Radeon HD 6950 |

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

| Chip | GF106 | Cayman |

| Architecture | Fermi | TeraScale 3 |

| Transistors | 1,170 million | 2,640 million |

| Die Size | 238 mm² | 389 mm² |

| Memory Size | 1024 MB | 2 GB |

| Memory Type | DDR3 | GDDR5 |

| Memory Bus | 128 bit | 256 bit |

| Memory Bandwidth | 28.80 GB/s | 160.0 GB/s |

| Shading Units | 144 | 1408 |

| TMUs | 24 | 88 |

| ROPs | 16 | 32 |

| Pixel Rate | 3.540 GPixel/s | 25.60 GPixel/s |

| Texture Rate | 14.16 GTexel/s | 70.40 GTexel/s |

| FP32 Performance | 339.8 GFLOPS | 2.253 TFLOPS |

| TDP | 35 W | 200 W |

| Power Connectors | None (Portable) | 2x 6-pin |

| OpenGL Version | 4.6 | 4.4 |

| Release Date | 2011-07-01 | 2010-12-13 |

Head-to-Head Benchmarks

The only benchmark in the data is the Geekbench OpenCL test, and it presents an unexpected result. The NVIDIA GeForce GT 555M scores 6493, while the AMD Radeon HD 6950 scores 6210. This gives the NVIDIA part a 4.6% victory, which is a curious outcome given the massive theoretical advantages of the AMD card. The HD 6950 has roughly 9.8 times more shading units and 5.6 times more memory bandwidth, yet it scores lower in this specific test.

This suggests that the Geekbench OpenCL workload might not be fully utilizing the HD 6950’s parallel architecture, or that its drivers were not as optimized for this particular test. The GT 555M’s score places it in the company of rivals like the NVIDIA Quadro M5000M and AMD Radeon Vega 10 Mobile, with deltaPct values of 0.2% and 0.3% respectively. The HD 6950’s score puts it near the AMD FirePro W600 and even the NVIDIA GeForce RTX 4070 Ti SUPER AD102, with deltaPct values of -0.2% and -0.9%. This implies that within this specific benchmark, the GT 555M is not just competitive with the HD 6950; it is on par with much newer and more powerful cards.

The single benchmark win for the GT 555M is its only victory, but it is a significant one in the context of the data. However, it is difficult to extrapolate this to general performance. The HD 6950’s enormous lead in pixel rate (25.60 GPixel/s vs 3.540 GPixel/s) and texture rate (70.40 GTexel/s vs 14.16 GTexel/s) would likely translate to a dominant performance in gaming or rendering tasks that are not captured by this single OpenCL test. The data suggests that while the GT 555M can hold its own in this compute benchmark, the HD 6950’s architecture is built for a different, more demanding class of workloads.

The Verdict

The choice between these two cards is dictated entirely by the use case. The NVIDIA GeForce GT 555M is the only option for a mobile platform. Its 35 W TDP and lack of external power connectors make it suitable for a laptop, and its benchmark score of 6493 shows it is a capable compute device for that form factor. Users needing GPU acceleration in a portable machine would find this chip sufficient.

The AMD Radeon HD 6950 is the clear choice for a desktop system where power and size are not limiting factors. Its 2 GB of GDDR5 memory, 160.0 GB/s of bandwidth, and 2.253 TFLOPS of FP32 compute performance make it a far more powerful piece of hardware on paper. While it loses the single Geekbench OpenCL test in this data, its architectural superiority suggests it would be the better performer in a wide range of other, more intensive tasks. Users who need a high-end desktop GPU for gaming or content creation, and who have a 550 W power supply and dual-slot space, should select the HD 6950. The GT 555M wins the benchmark, but the HD 6950 wins the hardware war.