AMD Radeon HD 6850 X2 vs NVIDIA GeForce 825M Comparison

The AMD Radeon HD 6850 X2 and the NVIDIA GeForce 825M represent two distinct approaches to graphics hardware from different eras, and the benchmark data reflects a clear, though narrow, performance advantage for the older dual-GPU card. In the single available benchmark, the Geekbench OpenCL test, the AMD Radeon HD 6850 X2 scores 3977, while the NVIDIA GeForce 825M scores 3694. This yields a 7.7% delta in favor of the AMD part, which also holds a percentile rank of 24 versus the NVIDIA’s 22. The data indicates that despite its age and significantly higher power draw, the AMD card delivers more raw compute throughput in this specific workload.

Where Each One Wins

The AMD Radeon HD 6850 X2 claims the only benchmark victory in the head-to-head comparison, winning the Geekbench OpenCL test with a score of 3977 against the NVIDIA GeForce 825M’s 3694. This 7.7% advantage positions the AMD card as the stronger choice for compute-oriented tasks that leverage OpenCL, as its dual-GPU configuration provides a substantial amount of parallel processing capability. The AMD card’s win is not isolated; its nearest rivals include the NVIDIA Quadro K2000 with an average score of 3964 and the GeForce 830M at 3957, placing it in a competitive performance tier despite its end-of-life status.

The NVIDIA GeForce 825M, while losing the benchmark comparison, does not have a corresponding win in any recorded test. However, its strengths lie outside raw compute scores. The data shows it operates at a 33 W TDP with no power connectors required, making it suitable for compact, power-constrained systems. Its architecture supports DirectX 12 (11_0), OpenGL 4.6, and Vulkan 1.2.175, offering broader API compatibility than the AMD card, which lacks Vulkan support entirely. For scenarios where power efficiency and modern API support are prioritized over peak compute performance, the GeForce 825M would be the more practical choice, despite the benchmark deficit.

Architecture Differences

The architectural divide between these two GPUs is substantial. The AMD Radeon HD 6850 X2 is built on the Barts chip using the TeraScale 2 architecture, fabricated on a 40 nm process at TSMC. It contains 1,700 million transistors on a 255 mm² die, yielding a transistor density of 6.7M per mm². This is a dual-GPU card, hence the "X2" designation, and it belongs to the Northern Islands (HD 6800) generation. In contrast, the NVIDIA GeForce 825M uses the GK208 chip based on the Kepler 2.0 architecture, produced on a more modern 28 nm process, also at TSMC. It packs 1,020 million transistors into a much smaller 87 mm² die, achieving a higher transistor density of 11.7M per mm².

The memory subsystems are drastically different. The AMD card features 2 GB of GDDR5 memory on a 256-bit bus, delivering 134.4 GB/s of bandwidth. The NVIDIA card has only 1024 MB of DDR3 memory on a 64-bit bus, resulting in a bandwidth of just 14.40 GB/s — a fraction of the AMD’s capability. This bandwidth disparity is a major factor in the compute performance gap. The AMD card also has far more execution resources: 960 shading units, 48 texture mapping units (TMUs), and 32 render output units (ROPs), compared to the NVIDIA’s 384 shading units, 32 TMUs, and 8 ROPs. The pixel rate of the AMD card is 25.60 GPixel/s versus 7.528 GPixel/s for the NVIDIA, and the texture rate is 38.40 GTexel/s versus 30.11 GTexel/s.

The process node differences also influence power characteristics. The AMD Radeon HD 6850 X2 has a TDP of 254 W, requiring dual 8-pin power connectors and a 600 W suggested PSU, while the NVIDIA GeForce 825M is an IGP (integrated graphics processor) with a 33 W TDP and no power connectors. The bus interface also differs: the AMD card uses PCIe 2.0 x16, while the NVIDIA uses PCIe 3.0 x8. Finally, the display outputs highlight their intended use cases — the AMD card provides 2x DVI, 1x HDMI 1.3a, and 1x DisplayPort 1.1, whereas the NVIDIA card’s outputs are described as "Portable Device Dependent," reflecting its mobile orientation.

Head-to-Head Benchmarks

The sole benchmark available for direct comparison is Geekbench OpenCL. In this test, the AMD Radeon HD 6850 X2 scores 3977, while the NVIDIA GeForce 825M scores 3694. The delta of 7.7% in favor of the AMD card is meaningful, though not overwhelming. To put this in context, the AMD card’s nearest rivals are the NVIDIA Quadro K2000 (3964, 0.3% behind) and the GeForce 830M (3957, 0.5% behind). This indicates that the Radeon HD 6850 X2 sits at the top of a tightly clustered group of similar-performing GPUs. On the NVIDIA side, the GeForce 825M’s nearest rivals include the GeForce GT 740M (3717, 0.6% ahead) and the Quadro 3000M (3718, 0.6% ahead), showing that the 825M is slightly below its immediate competitors, but still close.

The 7.7% performance gap between the two cards in this test can be attributed to the AMD’s massive advantages in memory bandwidth (134.4 GB/s vs. 14.40 GB/s) and shading unit count (960 vs. 384). The AMD card’s FP32 throughput is 1.536 TFLOPS, more than double the NVIDIA’s 722.7 GFLOPS. However, the NVIDIA card does have a higher boost clock of 941 MHz compared to the AMD’s unspecified base clock, though the AMD’s memory clock is higher at 1050 MHz (4.2 Gbps effective) versus the NVIDIA’s 900 MHz (1800 Mbps effective). In real-world terms, the benchmark results suggest that for OpenCL compute workloads, the older AMD card is the stronger performer, but the margin is modest enough that driver optimizations or workload-specific characteristics could narrow or invert the gap.

FAQ

Q: Which GPU has a higher score in the Geekbench OpenCL benchmark?

A: The AMD Radeon HD 6850 X2 scores 3977, which is 7.7% higher than the NVIDIA GeForce 825M’s score of 3694.

Q: How does the memory bandwidth compare between the two cards?

A: The AMD Radeon HD 6850 X2 has a memory bandwidth of 134.4 GB/s, which is dramatically higher than the NVIDIA GeForce 825M’s 14.40 GB/s, owing to its 256-bit GDDR5 interface versus the NVIDIA’s 64-bit DDR3.

Q: What are the TDP and power requirements of each GPU?

A: The AMD Radeon HD 6850 X2 has a TDP of 254 W and requires 2x 8-pin power connectors with a 600 W suggested PSU, while the NVIDIA GeForce 825M has a 33 W TDP, requires no power connectors, and has no suggested PSU listed.

Q: Does the NVIDIA GeForce 825M support Vulkan, and does the AMD card?

A: The NVIDIA GeForce 825M supports Vulkan 1.2.175, while the AMD Radeon HD 6850 X2 has no Vulkan support listed in its API specifications.

Q: What is the process node and transistor count for each chip?

A: The AMD Radeon HD 6850 X2 uses a 40 nm process with 1,700 million transistors, whereas the NVIDIA GeForce 825M uses a 28 nm process with 1,020 million transistors.

Q: Which card has more shading units and higher pixel rate?

A: The AMD Radeon HD 6850 X2 has 960 shading units and a pixel rate of 25.60 GPixel/s, compared to the NVIDIA GeForce 825M’s 384 shading units and 7.528 GPixel/s pixel rate.

Specification Differences

The two GPUs differ across nearly every major specification. The AMD Radeon HD 6850 X2 uses the Barts chip with TeraScale 2 architecture, while the NVIDIA GeForce 825M uses the GK208 chip with Kepler 2.0 architecture. The manufacturing process is 40 nm for AMD and 28 nm for NVIDIA, with transistor counts of 1,700 million and 1,020 million, respectively. Die sizes are 255 mm² for AMD and 87 mm² for NVIDIA, resulting in transistor densities of 6.7M / mm² and 11.7M / mm².

Memory configurations are starkly different: the AMD card has 2 GB of GDDR5 on a 256-bit bus, while the NVIDIA card has 1024 MB of DDR3 on a 64-bit bus. Memory bandwidth is 134.4 GB/s versus 14.40 GB/s. The AMD card has 960 shading units, 48 TMUs, and 32 ROPs, while the NVIDIA card has 384 shading units, 32 TMUs, and 8 ROPs. Pixel rates are 25.60 GPixel/s and 7.528 GPixel/s, and texture rates are 38.40 GTexel/s and 30.11 GTexel/s. FP32 performance is 1.536 TFLOPS for AMD and 722.7 GFLOPS for NVIDIA.

Power and physical requirements also diverge: the AMD card has a 254 W TDP, dual-slot width, 2x 8-pin power connectors, and a 600 W suggested PSU, while the NVIDIA card has a 33 W TDP, IGP slot width, no power connectors, and no suggested PSU. The bus interface is PCIe 2.0 x16 for AMD and PCIe 3.0 x8 for NVIDIA. Display outputs are 2x DVI, 1x HDMI 1.3a, and 1x DisplayPort 1.1 for AMD, versus "Portable Device Dependent" for NVIDIA. API support differs in that the AMD card supports DirectX 11.2 (11_0) and OpenGL 4.4 but no Vulkan, while the NVIDIA card supports DirectX 12 (11_0), OpenGL 4.6, and Vulkan 1.2.175. The memory clocks are 1050 MHz (4.2 Gbps effective) for AMD and 900 MHz (1800 Mbps effective) for NVIDIA, with the NVIDIA card having a base clock of 850 MHz and boost clock of 941 MHz, while the AMD card’s base clock is not listed.