AMD Radeon HD 6850 X2 vs NVIDIA GeForce GT 755M Comparison

The NVIDIA GeForce GT 755M and the AMD Radeon HD 6850 X2 are both end-of-life graphics products, but they represent radically different design philosophies. The GT 755M is a mobile-first, power-efficient Kepler part from NVIDIA’s GeForce 700M generation, while the HD 6850 X2 is a dual-GPU desktop card from AMD’s Northern Islands family built on TeraScale 2. The benchmark data shows a single head-to-head comparison in Geekbench OpenCL, where the NVIDIA part wins decisively. However, the underlying specifications tell a more nuanced story about memory bandwidth, raw compute, and power requirements. This analysis breaks down where each card wins, what the numbers actually mean, and which user should pay attention to which product.

Where Each One Wins

The data-driven verdict is clear on raw performance: the NVIDIA GeForce GT 755M wins the only shared benchmark. In Geekbench OpenCL, the GT 755M scores 4934, while the AMD Radeon HD 6850 X2 scores 3977. That is a 24.1% delta in NVIDIA’s favor. This is the sole head-to-head test available, so any claim about multi-core or gaming superiority must be tempered by the fact that only one metric exists. Still, a 24.1% lead in a compute-oriented API benchmark is substantial and not a marginal edge.

Where the AMD card wins is in theoretical throughput and memory bandwidth, though these do not translate into a benchmark victory here. The HD 6850 X2 has 960 shading units, 48 texture mapping units, and 32 raster operations pipelines, versus 384 shading units, 32 TMUs, and 16 ROPs on the GT 755M. The AMD card’s FP32 compute is 1.536 TFLOPS, nearly double the GT 755M’s 783.4 GFLOPS. Its memory bus is 256-bit, yielding 134.4 GB/s of bandwidth, compared to the GT 755M’s 128-bit bus and 86.40 GB/s. The AMD card also has a higher pixel rate (25.60 GPixel/s vs 8.160 GPixel/s) and texture rate (38.40 GTexel/s vs 32.64 GTexel/s). In raw silicon capability, the HD 6850 X2 appears superior on paper, but the actual OpenCL result contradicts that.

The GT 755M wins on efficiency and form factor. Its TDP is 50 W, versus 254 W for the HD 6850 X2. The NVIDIA card is an MXM Module, while the AMD card is a Dual-slot desktop part requiring 2x 8-pin power connectors and a 600 W suggested PSU. The GT 755M needs no external power connectors and runs on PCIe 3.0 x16, while the AMD card uses PCIe 2.0 x16. For a laptop or small-form-factor system, the GT 755M is the only viable choice. The AMD card is a power-hungry desktop monster.

The Verdict

The data points to the NVIDIA GeForce GT 755M as the better performer in the only test that matters. Its Geekbench OpenCL score of 4934 beats the AMD Radeon HD 6850 X2’s 3977 by 24.1%. If the sole criterion is this benchmark, the GT 755M wins outright. The average benchmark score for the GT 755M is 4033, while the HD 6850 X2 averages 3977. The GT 755M also sits at the 24th percentile of all GPUs, same as the AMD card, but with a higher average score.

Who should pick the GT 755M? Anyone who needs a mobile GPU, given its MXM slot width, 50 W TDP, and no power connectors. It is also the choice for users prioritizing compute performance in OpenCL workloads, as the data shows a clear lead. The GT 755M supports Vulkan 1.2.175 and DirectX 12 (11_0), while the AMD card has no Vulkan support and only DirectX 11.2 (11_0). For modern API compatibility, NVIDIA wins.

Who should pick the HD 6850 X2? Users who need raw memory bandwidth and higher pixel throughput, based on the spec sheet. The 134.4 GB/s bandwidth and 25.60 GPixel/s pixel rate are more than 50% higher than the GT 755M’s equivalents. But the benchmark does not reflect this advantage. The HD 6850 X2 also has a higher transistor count (1,700 million vs 1,270 million) and a larger die (255 mm² vs 118 mm²), but it is built on an older 40 nm process versus 28 nm. If a workload is bandwidth-bound and not captured by OpenCL, the AMD card might theoretically excel, but no data supports that claim. The verdict, strictly from the data: the GT 755M is the safer, better-performing choice.

Head-to-Head Benchmarks

The only head-to-head benchmark is Geekbench OpenCL. The NVIDIA GeForce GT 755M scores 4934, and the AMD Radeon HD 6850 X2 scores 3977. The delta is 24.1% in NVIDIA’s favor. This is a significant margin, especially considering the AMD card’s ostensibly superior compute specs. The GT 755M has half the shading units (384 vs 960) and less than half the FP32 throughput (783.4 GFLOPS vs 1.536 TFLOPS), yet it outperforms in this test. This suggests the OpenCL benchmark favors the NVIDIA architecture, or the dual-GPU configuration of the HD 6850 X2 does not scale efficiently in this workload. The HD 6850 X2 is literally two GPUs on one card, but the single benchmark score of 3977 does not reflect any dual-GPU scaling advantage.

The GT 755M’s nearest rivals in the database include the AMD Radeon HD 6850 X2 itself, with a deltaPct of 1.4% in NVIDIA’s favor on average scores. The GT 755M’s average score is 4033, while the HD 6850 X2’s is 3977. Other rivals include the AMD FirePro M4150 (4013, 0.5% behind) and the Intel HD Graphics 630 (4075, 1% ahead). The HD 6850 X2’s nearest rivals include the NVIDIA Quadro K2000 (3964, 0.3% behind) and the NVIDIA GeForce 830M (3957, 0.5% behind). These percentile data points show both cards are in a similar performance class, but the GT 755M edges ahead in the actual head-to-head.

FAQ

Q: Which GPU has a higher Geekbench OpenCL score?

A: The NVIDIA GeForce GT 755M scores 4934, which is 24.1% higher than the AMD Radeon HD 6850 X2’s 3977.

Q: Does the AMD Radeon HD 6850 X2 have any benchmark advantage?

A: No. The only shared benchmark is Geekbench OpenCL, where the AMD card loses. Its average benchmark score is 3977, lower than the GT 755M’s 4033.

Q: What is the memory bandwidth difference?

A: The AMD Radeon HD 6850 X2 has 134.4 GB/s of bandwidth on a 256-bit bus, while the NVIDIA GeForce GT 755M has 86.40 GB/s on a 128-bit bus. The AMD card has 55.6% more bandwidth.

Q: Which card supports Vulkan?

A: Only the NVIDIA GeForce GT 755M supports Vulkan, with version 1.2.175. The AMD Radeon HD 6850 X2 has no Vulkan support listed.

Q: How do their power requirements differ?

A: The GT 755M has a 50 W TDP and uses no power connectors. The HD 6850 X2 has a 254 W TDP and requires 2x 8-pin power connectors, with a suggested PSU of 600 W.

Q: Are they in the same performance percentile?

A: Yes, both are at the 24th percentile of all GPUs. However, the GT 755M has a higher average benchmark score (4033 vs 3977).

Architecture Differences

The two GPUs come from different architectural generations. The NVIDIA GeForce GT 755M uses the GK107 chip based on Kepler architecture, built on a 28 nm process at TSMC. It has 1,270 million transistors on a 118 mm² die, yielding a transistor density of 10.8 million per square millimeter. Kepler is a modern architecture that supports DirectX 12 (11_0), OpenGL 4.6, and Vulkan 1.2.175. The GT 755M belongs to the GeForce 700M generation, with predecessors in GeForce 600M and successors in GeForce 800M.

The AMD Radeon HD 6850 X2 uses the Barts chip based on TeraScale 2 architecture, built on a 40 nm process at TSMC. It has 1,700 million transistors on a 255 mm² die, with a lower transistor density of 6.7 million per square millimeter. TeraScale 2 supports DirectX 11.2 (11_0) and OpenGL 4.4, but no Vulkan. This card is part of the Northern Islands (HD 6800) generation, following Evergreen and preceding Southern Islands. The 40 nm process is older and less dense than the 28 nm used by NVIDIA.

The AMD card is a dual-GPU product, as indicated by its name (X2), while the GT 755M is a single-GPU mobile part. The AMD card’s slot width is Dual-slot, and it has display outputs of 2x DVI, 1x HDMI 1.3a, and 1x DisplayPort 1.1. The GT 755M’s display outputs are listed as “Portable Device Dependent,” reflecting its mobile nature. The GT 755M has no power connectors, while the AMD card requires 2x 8-pin connectors.

Specification Differences

The specification differences are stark. The NVIDIA GeForce GT 755M has 384 shading units, 32 TMUs, and 16 ROPs. The AMD Radeon HD 6850 X2 has 960 shading units, 48 TMUs, and 32 ROPs. The AMD card has more than double the shading units and double the ROPs. Clock speeds differ: the GT 755M has a base clock of 980 MHz and a boost clock of 1020 MHz, while the HD 6850 X2 has no base or boost clock listed. Memory clocks are 1350 MHz (5.4 Gbps effective) for NVIDIA and 1050 MHz (4.2 Gbps effective) for AMD.

Memory configuration: both have 2 GB of GDDR5, but the bus width differs. The GT 755M uses a 128-bit bus, while the HD 6850 X2 uses a 256-bit bus. This leads to the bandwidth difference: 86.40 GB/s vs 134.4 GB/s. Pixel rate is 8.160 GPixel/s for NVIDIA and 25.60 GPixel/s for AMD. Texture rate is 32.64 GTexel/s for NVIDIA and 38.40 GTexel/s for AMD. FP32 compute is 783.4 GFLOPS for NVIDIA and 1.536 TFLOPS for AMD.

Power and form factor: the GT 755M has a 50 W TDP and uses an MXM Module slot, with no power connectors. The HD 6850 X2 has a 254 W TDP, is a Dual-slot card, and requires 2x 8-pin connectors with a 600 W suggested PSU. The bus interface is PCIe 3.0 x16 for NVIDIA and PCIe 2.0 x16 for AMD. The GT 755M has no length, height, or width dimensions listed, nor does the AMD card. The GT 755M was released on 2013-06-24, while the HD 6850 X2 was released on 2011-09-18. Both are end-of-life products.