AMD Radeon R7 M340 vs AMD Radeon RX 6400 Comparison

Where Each One Wins

The benchmark data splits cleanly in favor of the AMD Radeon RX 6400, which wins both recorded head-to-head tests. The R7 M340 does not claim a single victory in any shared benchmark. The RX 6400’s advantage is not marginal; it is transformative in compute workloads and substantial in graphics API performance.

For OpenCL compute, the RX 6400 posts a score of 32011 against the R7 M340’s 4932, a 549% delta. This is the kind of gap that separates generations of architecture, not just clock speed tweaks. In Vulkan, the RX 6400 scores 16372 versus 5193, a 215.3% lead. Any workload that leans on modern graphics APIs, such as recent game titles or GPU-accelerated rendering, will favor the RX 6400 overwhelmingly.

The R7 M340 is not without a niche, but the data does not support it in raw performance. Its only recorded benchmarks are the same two tests, and in both it lands far behind. The database places the RX 6400 at the 35th percentile among all GPUs, while the R7 M340 sits at the 30th percentile. That difference is small in percentile terms, but the actual score gap is large: the RX 6400’s average benchmark score is 6001 versus 5063 for the R7 M340. The percentile ranking is compressed because many other GPUs occupy the lower mid-range, but within this pair, the RX 6400 is the clear performance leader.

For a builder choosing between these two, the use case is simple: if you need any level of modern gaming or compute acceleration, the RX 6400 is the only sensible pick. The R7 M340 is limited to older, lighter workloads where its GCN 3.0 architecture and 2 GB of DDR3 can still function, but it will struggle with anything beyond basic 2D acceleration or legacy DirectX 9 content.

Architecture Differences

The two GPUs belong to completely different design eras. The RX 6400 uses the Navi 24 chip built on RDNA 2.0 architecture, fabricated on a 6 nm process at TSMC. The R7 M340 uses the Meso chip with GCN 3.0 architecture, fabricated on a 28 nm process, also at TSMC. The process node difference alone, 6 nm versus 28 nm, explains a large portion of the performance and efficiency gap.

Transistor counts tell the story of design philosophy. The RX 6400 packs 5,400 million transistors into a 107 mm² die, yielding a density of 50.5 million transistors per square millimeter. The R7 M340 has 1,550 million transistors on a larger 125 mm² die, with a density of only 12.4 million per square millimeter. The RX 6400 crams more than three times the transistors into a smaller physical area.

Memory architecture differs fundamentally. The RX 6400 uses 4 GB of GDDR6 on a 64-bit bus, delivering 128.0 GB/s of bandwidth. The R7 M340 uses 2 GB of DDR3 on the same 64-bit bus, but only achieves 16.00 GB/s. That is an 8x bandwidth gap, which directly impacts texture streaming, resolution scaling, and frame buffer performance.

The compute units are also on different scales. The RX 6400 has 768 shading units, 48 texture mapping units, and 32 render output units. It also includes 12 ray tracing cores, a feature entirely absent from the R7 M340. The R7 M340 has 320 shading units, 20 TMUs, and 8 ROPs. The RX 6400’s pixel rate is 74.27 GPixel/s versus 8.168 GPixel/s for the R7 M340. Texture rate is 111.4 GTexel/s versus 20.42 GTexel/s. FP32 compute is 3.565 TFLOPS versus 653.4 GFLOPS, a 5.5x difference.

Feature support also diverges. The RX 6400 supports DirectX 12 Ultimate (12_2) and Vulkan 1.4, while the R7 M340 only reaches DirectX 12 (12_0) and Vulkan 1.2.170. Both support OpenGL 4.6. The newer API support on the RX 6400 enables features like mesh shaders and variable rate shading, which the older GCN part cannot handle.

Power and interface details differ as well. The RX 6400 has a TDP of 53 W, requires no power connectors, and uses a PCIe 4.0 x4 interface. The R7 M340 has no recorded TDP, no listed power connector requirement, and uses a PCIe 3.0 x8 interface. The RX 6400 is a single-slot card with display outputs including 1x HDMI 2.1 and 1x DisplayPort 1.4a. The R7 M340 has no listed display outputs.

FAQ

Q: Which GPU is faster in OpenCL compute?

A: The AMD Radeon RX 6400 scores 32011 in Geekbench OpenCL, while the R7 M340 scores 4932. That is a 549% advantage for the RX 6400.

Q: Can the R7 M340 handle modern games?

A: The data shows it lacks support for DirectX 12 Ultimate and has only 2 GB of DDR3 memory with 16.00 GB/s bandwidth. It also has no ray tracing cores. Modern titles requiring DirectX 12_2 features will not run properly.

Q: Does the RX 6400 support ray tracing?

A: Yes, the RX 6400 includes 12 ray tracing cores and supports DirectX 12 Ultimate (12_2). The R7 M340 has no ray tracing cores.

Q: What is the memory bandwidth difference?

A: The RX 6400 delivers 128.0 GB/s using 4 GB of GDDR6 on a 64-bit bus. The R7 M340 delivers 16.00 GB/s using 2 GB of DDR3 on the same 64-bit bus. The RX 6400 has 8 times the bandwidth.

Q: Which GPU has a higher average benchmark score?

A: The RX 6400 has an average benchmark score of 6001, while the R7 M340 has 5063. The RX 6400 also sits at the 35th percentile among all GPUs, compared to the 30th percentile for the R7 M340.

Q: Are both cards end-of-life?

A: Yes, the database lists both as end-of-life. The RX 6400 was released on 2022-01-18, while the R7 M340 was released on 2015-05-04.

Specification Differences

| Specification | AMD Radeon RX 6400 | AMD Radeon R7 M340 |

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

| Chip | Navi 24 | Meso |

| Architecture | RDNA 2.0 | GCN 3.0 |

| Generation | Navi II (RX 6000) | Gem System (R7 M300) |

| Process Node | 6 nm | 28 nm |

| Transistors | 5,400 million | 1,550 million |

| Die Size | 107 mm² | 125 mm² |

| Transistor Density | 50.5M / mm² | 12.4M / mm² |

| Base Clock | 1923 MHz | 943 MHz |

| Boost Clock | 2321 MHz | 1021 MHz |

| Game Clock | 2039 MHz | N/A |

| Memory Clock | 2000 MHz (16 Gbps effective) | 1000 MHz (2 Gbps effective) |

| Memory Size | 4 GB | 2 GB |

| Memory Type | GDDR6 | DDR3 |

| Memory Bus Width | 64 bit | 64 bit |

| Memory Bandwidth | 128.0 GB/s | 16.00 GB/s |

| Shading Units | 768 | 320 |

| TMUs | 48 | 20 |

| ROPs | 32 | 8 |

| Ray Tracing Cores | 12 | None |

| Pixel Rate | 74.27 GPixel/s | 8.168 GPixel/s |

| Texture Rate | 111.4 GTexel/s | 20.42 GTexel/s |

| FP32 Performance | 3.565 TFLOPS | 653.4 GFLOPS |

| FP16 Performance | 7.130 TFLOPS (2:1) | 653.4 GFLOPS (1:1) |

| TDP | 53 W | Not listed |

| Bus Interface | PCIe 4.0 x4 | PCIe 3.0 x8 |

| DirectX Support | 12 Ultimate (12_2) | 12 (12_0) |

| Vulkan Support | 1.4 | 1.2.170 |

| Release Date | 2022-01-18 | 2015-05-04 |

| Launch MSRP | 159 USD | Not listed |

Head-to-Head Benchmarks

The only two shared benchmarks in the database are Geekbench OpenCL and Geekbench Vulkan. Both show the RX 6400 winning by enormous margins.

In Geekbench OpenCL, the RX 6400 scores 32011 against the R7 M340’s 4932. The delta is 549%. This test exercises general-purpose compute through the OpenCL API, which includes tasks like physics simulation, image processing, and machine learning inference. The RX 6400’s RDNA 2.0 architecture with 768 shading units and 3.565 TFLOPS of FP32 performance simply overwhelms the older GCN 3.0 part with 320 shading units and 653.4 GFLOPS. The R7 M340’s compute throughput is roughly one-sixth of the RX 6400’s, and the benchmark reflects that.

In Geekbench Vulkan, the RX 6400 scores 16372 versus 5193 for the R7 M340, a 215.3% delta. Vulkan is a low-overhead graphics API, and the RX 6400’s support for Vulkan 1.4, combined with its much higher texture rate (111.4 GTexel/s versus 20.42 GTexel/s) and pixel rate (74.27 GPixel/s versus 8.168 GPixel/s), gives it a massive advantage. The R7 M340’s Vulkan 1.2.170 support is functional but its hardware is too weak to translate API improvements into usable frame rates.

The RX 6400 also wins on aggregate metrics. Its average benchmark score of 6001 beats the R7 M340’s 5063. The RX 6400’s nearest rivals include the NVIDIA GeForce GTX 770M at 6000 (0% delta), the NVIDIA RTX PRO 6000 Blackwell Server at 5996 (0.1% delta), the AMD FirePro W4100 at 5987 (0.2% delta), and the NVIDIA Quadro K4000M at 5986 (0.3% delta). The R7 M340’s nearest rivals are much closer: the AMD Radeon R7 240 at 5063 (0% delta), the AMD FirePro W4170M at 5034 (0.6% delta), the AMD Radeon R5 M430 at 5018 (0.9% delta), and the AMD Radeon R7 Graphics at 4998 (1.3% delta). This shows the R7 M340 is in a performance class roughly 15% below the RX 6400’s class, and the head-to-head results amplify that gap in specific API tests.

The Verdict

The data leaves no ambiguity. The AMD Radeon RX 6400 is the superior product in every measurable way. It wins both head-to-head benchmarks, has a higher average score, a higher percentile ranking, and a more modern architecture. The R7 M340 is a legacy part from 2015 with GCN 3.0, 2 GB of DDR3, and no ray tracing support. It cannot compete in any modern workload that the RX 6400 can handle.

For a builder assembling a low-power, entry-level gaming or compute system, the RX 6400 is the clear choice. Its 53 W TDP, no power connector requirement, and 4 GB of GDDR6 make it a drop-in solution for basic desktops. The R7 M340, with no listed TDP or display outputs, appears suited only for pre-built laptops or OEM machines where upgradeability is irrelevant.

The R7 M340’s only possible advantage is its age and legacy compatibility. It supports DirectX 12 (12_0) and OpenGL 4.6, so it can run older titles that predate DirectX 12 Ultimate. But even there, its 16.00 GB/s memory bandwidth and 653.4 GFLOPS FP32 performance will limit it to very low resolutions and settings. The RX 6400, with 128.0 GB/s bandwidth and 3.565 TFLOPS, will run those same older titles at far higher quality.

Choose the RX 6400 for any application where performance matters. Choose the R7 M340 only if you are constrained by a proprietary system that physically cannot accept the RX 6400, or if your workload is so old and light that even the R7 M340’s 30th percentile ranking is overkill. For everyone else, the RX 6400’s 549% OpenCL lead and 215.3% Vulkan lead make the decision trivial.