AMD Radeon HD 6770 vs AMD Radeon HD 6850 X2 Comparison

The AMD Radeon HD 6850 X2 and AMD Radeon HD 6770 are both end-of-life graphics cards from AMD’s Northern Islands generation, built on the TeraScale 2 architecture and fabricated by TSMC on a 40 nm process. While they share a common architectural lineage, their positioning within the lineup is distinct, and benchmark data reveals a clear performance hierarchy between the two. The HD 6850 X2, a dual-GPU card, posts a Geekbench OpenCL score of 3977, while the HD 6770 achieves 3649, a difference of exactly 9% in favor of the larger card.

Head-to-Head Benchmarks

The single available head-to-head benchmark—Geekbench OpenCL—shows a decisive win for the AMD Radeon HD 6850 X2. The HD 6850 X2 scores 3977, while the HD 6770 scores 3649, yielding a deltaPct of 9% in favor of the X2. This is not a marginal victory; it represents a meaningful gap in raw compute throughput that would translate into tangible differences in OpenCL-accelerated workloads.

To contextualize the HD 6850 X2’s score, its nearest rival is the NVIDIA Quadro K2000, which averages 3964—a mere 0.3% difference. The HD 6850 X2 also edges out the NVIDIA GeForce 830M (3957, 0.5% behind) and the AMD Radeon R5 M420 (3956, 0.5% behind). This cluster of scores indicates that the HD 6850 X2 sits at a performance plateau where tiny margins separate it from several mid-range mobile and workstation GPUs. Its 24th percentile ranking among all GPUs suggests it outperforms roughly a quarter of the database, a modest but not negligible standing.

The HD 6770, meanwhile, trails its nearest rivals in both directions. It scores 0.6% above the NVIDIA GeForce GTX 1050 (3629) and 0.9% above the NVIDIA GeForce GT 735M (3616), but it falls 1.2% short of the NVIDIA GeForce 825M (3694) and sits 1.5% above the NVIDIA RTX 5000 Mobile Ada Generation (3596). The HD 6770’s 22nd percentile ranking places it just two percentage points below the HD 6850 X2 in overall standing, yet the 9% benchmark gap between the two cards is substantial.

The deltaPct of 9% between the two AMD cards is larger than any of the deltas seen in their respective nearest-rival clusters, reinforcing that the HD 6850 X2 is meaningfully faster in this test. For context, the HD 6850 X2’s 3977 score is 328 points higher than the HD 6770’s 3649—a difference that would be perceptible in compute-heavy applications.

Architecture Differences

Despite sharing the TeraScale 2 architecture and the 40 nm TSMC process node, the two cards diverge significantly in their underlying silicon. The HD 6850 X2 uses the Barts chip, which contains 1,700 million transistors on a 255 mm² die, yielding a transistor density of 6.7M per mm². The HD 6770 employs the Juniper chip, with 1,040 million transistors on a 166 mm² die and a density of 6.3M per mm². The Barts chip is thus 63% larger in transistor count and 54% larger in die area, reflecting a more complex and capable design.

Memory configurations differ sharply. The HD 6850 X2 features 2 GB of GDDR5 memory on a 256-bit bus, delivering 134.4 GB/s of bandwidth. Its memory clock is 1050 MHz, which translates to 4.2 Gbps effective. The HD 6770, by contrast, has half the memory (1024 MB), a 128-bit bus, and 76.80 GB/s of bandwidth—roughly 43% less than the X2. Its memory clock runs at 1200 MHz, or 4.8 Gbps effective, meaning the HD 6770’s memory operates at a higher raw frequency but on a narrower bus, resulting in far lower aggregate bandwidth.

Compute resources also favor the HD 6850 X2. It packs 960 shading units, 48 texture mapping units (TMUs), and 32 raster output units (ROPs). The HD 6770 has 800 shading units, 40 TMUs, and only 16 ROPs. The ROP disparity is particularly stark: the HD 6850 X2 has exactly double the ROP count, which directly impacts pixel fill rate. The X2 achieves 25.60 GPixel/s, while the HD 6770 manages 13.60 GPixel/s—again a doubling. Texture rate is closer: 38.40 GTexel/s for the X2 versus 34.00 GTexel/s for the HD 6770, a 13% advantage for the larger card.

Peak FP32 throughput tells a similar story. The HD 6850 X2 delivers 1.536 TFLOPS, while the HD 6770 produces 1,360.0 GFLOPS (1.36 TFLOPS). The X2 leads by roughly 13% in raw floating-point performance, though the benchmark gap of 9% suggests real-world efficiency differences narrow the theoretical advantage slightly.

Power delivery and board design reflect the performance gap. The HD 6850 X2 has a TDP of 254 W, requires two 8-pin power connectors, and recommends a 600 W power supply. The HD 6770 is far more modest: 108 W TDP, a single 6-pin connector, and a 300 W suggested PSU. Both cards are dual-slot designs, and both use a PCIe 2.0 x16 interface.

Where Each One Wins

The HD 6850 X2 wins the only direct benchmark, and its architectural advantages point to specific use cases where it would excel. Its doubled ROP count and higher pixel rate (25.60 GPixel/s versus 13.60 GPixel/s) make it markedly better suited for resolutions and settings that stress fill-rate, such as high-resolution rendering with heavy post-processing effects. The 2 GB memory capacity and 134.4 GB/s bandwidth also give it a clear edge in texture-heavy workloads and larger frame buffers, where the HD 6770’s 1 GB and 76.80 GB/s could become a bottleneck.

The HD 6850 X2’s higher transistor count (1,700 million versus 1,040 million) and larger die (255 mm² versus 166 mm²) indicate a more robust compute core, which aligns with its 9% OpenCL lead. For compute tasks like OpenCL-accelerated video encoding, physics simulation, or data-parallel workloads, the X2 is the stronger choice. Its 960 shading units versus 800 provide a 20% advantage in raw shader count, which should translate to better performance in shader-bound games and GPGPU applications.

The HD 6770, despite losing the head-to-head, has its own territory. Its lower TDP of 108 W versus 254 W makes it far easier to cool and power—a single 6-pin connector and 300 W PSU recommendation mean it can slot into systems with modest power supplies. Its compact 198 mm (7.8 inches) length, noted in its specifications, gives it an edge in small-form-factor builds where the HD 6850 X2’s larger dual-GPU board might not fit. The HD 6770 also offers a different display configuration: 2x DVI, 1x HDMI 1.3a, and 2x mini-DisplayPort 1.1, versus the X2’s 2x DVI, 1x HDMI 1.3a, and a single DisplayPort 1.1. For multi-monitor setups requiring more than one DisplayPort connection, the HD 6770’s dual mini-DP outputs are more flexible.

In terms of overall standing, the HD 6850 X2’s 24th percentile versus the HD 6770’s 22nd percentile is a narrow margin, but the benchmark delta is not. The X2 is the performance pick; the HD 6770 is the efficiency and compatibility pick.

FAQ

Q: Which card has a higher Geekbench OpenCL score?

A: The AMD Radeon HD 6850 X2 scores 3977, while the AMD Radeon HD 6770 scores 3649, giving the X2 a 9% lead.

Q: How do the two cards compare in memory bandwidth?

A: The HD 6850 X2 offers 134.4 GB/s over a 256-bit bus with 2 GB GDDR5, while the HD 6770 provides 76.80 GB/s over a 128-bit bus with 1024 MB GDDR5.

Q: What are the power supply requirements for each card?

A: The HD 6850 X2 has a 254 W TDP and recommends a 600 W PSU with two 8-pin connectors. The HD 6770 has a 108 W TDP and recommends a 300 W PSU with one 6-pin connector.

Q: Which card has more ROPs and what does that affect?

A: The HD 6850 X2 has 32 ROPs versus the HD 6770’s 16, resulting in a pixel rate of 25.60 GPixel/s for the X2 compared to 13.60 GPixel/s for the HD 6770, favoring the X2 in fill-rate-bound scenarios.

Q: Are both cards based on the same architecture?

A: Yes, both use AMD’s TeraScale 2 architecture and are fabricated on a 40 nm process by TSMC, but they use different chips: Barts for the HD 6850 X2 and Juniper for the HD 6770.

Q: What is the launch MSRP of the HD 6770?

A: The AMD Radeon HD 6770 had a launch MSRP of 129 USD.

Specification Differences

| Specification | AMD Radeon HD 6850 X2 | AMD Radeon HD 6770 |

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

| Chip | Barts | Juniper |

| Transistors | 1,700 million | 1,040 million |

| Die Size | 255 mm² | 166 mm² |

| Transistor Density | 6.7M / mm² | 6.3M / mm² |

| Memory Clock | 1050 MHz (4.2 Gbps effective) | 1200 MHz (4.8 Gbps effective) |

| Memory Size | 2 GB | 1024 MB |

| Memory Bus Width | 256 bit | 128 bit |

| Memory Bandwidth | 134.4 GB/s | 76.80 GB/s |

| Shading Units | 960 | 800 |

| TMUs | 48 | 40 |

| ROPs | 32 | 16 |

| Pixel Rate | 25.60 GPixel/s | 13.60 GPixel/s |

| Texture Rate | 38.40 GTexel/s | 34.00 GTexel/s |

| FP32 | 1.536 TFLOPS | 1,360.0 GFLOPS |

| TDP | 254 W | 108 W |

| Power Connectors | 2x 8-pin | 1x 6-pin |

| Suggested PSU | 600 W | 300 W |

| Display Outputs | 2x DVI, 1x HDMI 1.3a, 1x DisplayPort 1.1 | 2x DVI, 1x HDMI 1.3a, 2x mini-DisplayPort 1.1 |

| Length | Not listed | 198 mm (7.8 inches) |

| Release Date | 2011-09-18 | 2011-01-20 |

| Launch MSRP | Not listed | 129 USD |

| Geekbench OpenCL Score | 3977 | 3649 |

| Percentile vs All GPUs | 24 | 22 |