AMD Radeon HD 6770 vs AMD Radeon R5 M420 Comparison

AMD Radeon R5 M420 and AMD Radeon HD 6770 represent two distinct eras of AMD mobile and desktop graphics, separated by five years of architectural evolution. The data shows a single head-to-head benchmark result: the R5 M420 scores 3956 in Geekbench OpenCL, while the HD 6770 scores 3649, giving the newer chip an 8.4% advantage. This margin, however, masks fundamental differences in design philosophy, memory subsystems, and feature support that dictate where each card remains relevant today.

Where Each One Wins

The R5 M420 wins the only direct comparison available, taking the Geekbench OpenCL test by 8.4% (3956 vs 3649). This victory is notable because the R5 M420 achieves it with far fewer resources on paper — 320 shading units versus 800, 20 texture units versus 40, and 8 ROPs versus 16. The win suggests that architectural efficiency under GCN 1.0 outweighs raw hardware counts from the older TeraScale 2 design.

The HD 6770, despite losing the OpenCL benchmark, retains advantages in memory bandwidth and raw throughput metrics that favor certain workloads. Its 76.80 GB/s bandwidth is 4.8 times higher than the R5 M420's 16.00 GB/s, and its 1,360.0 GFLOPS FP32 performance is 2.5 times higher. These figures indicate the HD 6770 would likely win in memory-bandwidth-bound scenarios or tasks that scale with raw shader count, even though the single benchmark does not capture such a win.

The R5 M420's victory places it at the 23rd percentile among all GPUs, one point higher than the HD 6770's 22nd percentile. This ranking difference is small, but the benchmark data shows the newer part edges ahead in compute tasks while the older card's strengths lie in theoretical peak throughput that modern API overhead may not fully utilize.

Architecture Differences

The R5 M420 uses the Jet chip built on GCN 1.0 architecture, fabricated on a 28 nm process at TSMC. It packs 690 million transistors into a 56 mm² die, yielding a transistor density of 12.3 million per square millimeter. This compact design operates as an integrated graphics processor (IGP) with a base clock of 780 MHz and boost up to 850 MHz, paired with 4 GB of DDR3 memory on a 64-bit bus.

The HD 6770 uses the Juniper chip based on TeraScale 2 architecture, built on a 40 nm process, also at TSMC. This older design contains 1,040 million transistors across a 166 mm² die, with a transistor density of just 6.3 million per square millimeter. It runs as a dual-slot desktop card with a 108 W TDP, requiring a 300 W suggested power supply and a single 6-pin power connector. Its memory is 1024 MB of GDDR5 on a 128-bit bus, clocked at 1200 MHz with 4.8 Gbps effective speed.

The architectural gulf is stark: GCN 1.0 was designed for compute-heavy DirectX 12 workloads, while TeraScale 2 predates unified shader architectures that handle modern APIs efficiently. The R5 M420 supports DirectX 12 (11_1), OpenGL 4.6, and Vulkan 1.2.170, whereas the HD 6770 tops out at DirectX 11.2 (11_0) and OpenGL 4.4, with no Vulkan support. The R5 M420 also uses a PCIe 3.0 x8 interface, while the HD 6770 relies on PCIe 2.0 x16.

FAQ

Q: Which card has better memory bandwidth?

A: The HD 6770 offers 76.80 GB/s bandwidth from 1024 MB of GDDR5 on a 128-bit bus, while the R5 M420 provides 16.00 GB/s from 4 GB of DDR3 on a 64-bit bus — a 4.8x difference favoring the older card.

Q: Does the R5 M420 support modern graphics APIs?

A: Yes. The R5 M420 supports DirectX 12 (11_1), OpenGL 4.6, and Vulkan 1.2.170, while the HD 6770 is limited to DirectX 11.2 (11_0) and OpenGL 4.4, with no Vulkan support.

Q: What is the power requirement for each card?

A: The HD 6770 has a 108 W TDP, requires a 300 W suggested power supply, and needs one 6-pin power connector. The R5 M420 has no listed TDP and operates as an integrated GPU with no power connectors.

Q: How do their shading resources compare?

A: The HD 6770 has 800 shading units, 40 texture units, and 16 ROPs, while the R5 M420 has 320 shading units, 20 texture units, and 8 ROPs — the HD 6770 has 2.5x more shading units.

Q: Which card is newer and what process node does it use?

A: The R5 M420 was released in 2016 and uses a 28 nm process, while the HD 6770 was released in 2011 and uses a 40 nm process. The newer node allows the R5 M420 to pack 12.3M transistors per square millimeter versus 6.3M for the HD 6770.

Q: What are the physical size differences?

A: The HD 6770 is a dual-slot card measuring 198 mm (7.8 inches) in length, while the R5 M420 is an IGP with no listed dimensions and a slot width of "IGP," meaning it is integrated onto a motherboard.

Specification Differences

| Specification | AMD Radeon R5 M420 | AMD Radeon HD 6770 |

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

| Chip | Jet | Juniper |

| Architecture | GCN 1.0 | TeraScale 2 |

| Process Node | 28 nm | 40 nm |

| Transistors | 690 million | 1,040 million |

| Die Size | 56 mm² | 166 mm² |

| Transistor Density | 12.3M / mm² | 6.3M / mm² |

| Base Clock | 780 MHz | — |

| Boost Clock | 850 MHz | — |

| Memory Clock | 1000 MHz (2 Gbps effective) | 1200 MHz (4.8 Gbps effective) |

| Memory Size | 4 GB | 1024 MB |

| Memory Type | DDR3 | GDDR5 |

| Memory Bus Width | 64 bit | 128 bit |

| Memory Bandwidth | 16.00 GB/s | 76.80 GB/s |

| Shading Units | 320 | 800 |

| TMUs | 20 | 40 |

| ROPs | 8 | 16 |

| Pixel Rate | 6.800 GPixel/s | 13.60 GPixel/s |

| Texture Rate | 17.00 GTexel/s | 34.00 GTexel/s |

| FP32 | 544.0 GFLOPS | 1,360.0 GFLOPS |

| TDP | — | 108 W |

| Slot Width | IGP | Dual-slot |

| Power Connectors | — | 1x 6-pin |

| Suggested PSU | — | 300 W |

| Bus Interface | PCIe 3.0 x8 | PCIe 2.0 x16 |

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

| DirectX | 12 (11_1) | 11.2 (11_0) |

| OpenGL | 4.6 | 4.4 |

| Vulkan | 1.2.170 | — |

| Release Date | 2016-05-14 | 2011-01-20 |

| Launch MSRP | — | 129 USD |

Head-to-Head Benchmarks

The single benchmark result — Geekbench OpenCL — shows the R5 M420 scoring 3956 against the HD 6770's 3649, a delta of 8.4% in favor of the newer part. This result is surprising given the HD 6770's theoretical advantages: it has 2.5x more shading units (800 vs 320), 2x the texture units (40 vs 20), 2x the ROPs (16 vs 8), and 4.8x the memory bandwidth (76.80 vs 16.00 GB/s). The HD 6770 also delivers 2.5x the FP32 performance (1,360.0 vs 544.0 GFLOPS) and 2x the pixel rate (13.60 vs 6.800 GPixel/s).

The R5 M420's victory despite these deficits points to GCN 1.0's superior compute efficiency and modern driver optimizations for OpenCL workloads. The 28 nm process allows higher clock efficiency per watt, and the architecture's design for parallel compute tasks likely compensates for fewer raw resources. The HD 6770's nearest rivals include the NVIDIA GeForce GTX 1050 (score 3629, delta 0.6%) and GeForce GT 735M (score 3616, delta 0.9%), placing its performance in a similar bracket to entry-level desktop and mobile parts. The R5 M420's nearest rivals — NVIDIA GeForce 830M (3957, delta 0%) and GeForce GT 745M (3953, delta 0.1%) — show it sits at parity with mid-range mobile GPUs from the same era.

The Verdict

The data supports choosing the R5 M420 for compute-oriented tasks and modern API compatibility. Its 8.4% lead in Geekbench OpenCL, combined with support for DirectX 12, Vulkan 1.2.170, and OpenGL 4.6, makes it the more future-proof option despite having a fraction of the HD 6770's raw throughput. The newer 28 nm process and GCN 1.0 architecture deliver better efficiency per transistor, as evidenced by its higher benchmark score with 34% fewer transistors (690 million vs 1,040 million).

The HD 6770 remains relevant for scenarios that demand maximum memory bandwidth or raw shader throughput. Its 76.80 GB/s bandwidth, 1,360.0 GFLOPS FP32, and 800 shading units make it preferable for older games or applications that scale with these metrics and do not require Vulkan support. Its 108 W TDP and dual-slot form factor, however, restrict it to desktop use with a 300 W power supply, while the R5 M420's IGP design requires no additional power.

The HD 6770's launch MSRP was 129 USD, reflecting its original desktop market position, whereas the R5 M420 has no listed launch price, consistent with its integrated mobile deployment. Users with modern software stacks should favor the R5 M420 for its API support and benchmark lead; those running legacy 32-bit applications that thrash memory should consider the HD 6770's bandwidth advantage. The percentile rankings — 23rd for the R5 M420, 22nd for the HD 6770 — confirm these are entry-level parts, but the newer architecture wins where it counts in current benchmarks.