AMD Radeon RX 6400 vs NVIDIA GeForce 840M Comparison

Head-to-Head Benchmarks

The benchmark data leaves no ambiguity: the AMD Radeon RX 6400 wins both recorded head-to-head comparisons against the NVIDIA GeForce 840M, and it wins them by margins that are not close. In Geekbench OpenCL, the RX 6400 scores 32,011 points against 5,764 for the 840M, a 455.4% advantage. That is not a marginal generational step; it is a complete category gap. In Geekbench Vulkan, the RX 6400 scores 16,372 against 4,880, a 235.5% lead. Both results place the RX 6400 firmly ahead in compute-oriented workloads, and the gap is large enough that the 840M cannot compensate in any measured test.

The RX 6400 also holds a substantial lead in the broader aggregate metrics. Its average benchmark score is 6,001, while the 840M averages 5,322. That 679-point gap is meaningful, though it understates how much faster the RX 6400 is in the two tests both cards actually share. The percentile rankings tell a similar story: the RX 6400 sits at the 35th percentile of all GPUs in the database, while the 840M sits at the 31st. Neither card is near the top of the field, but the RX 6400 is clearly the stronger of the two.

Looking at the RX 6400 in isolation, its individual benchmark results show a mixed profile. Its Passmark G3D score is 7,673, which is respectable for its class, and its Passmark G2D score of 722 indicates competent 2D performance. Compute workloads are where it shines: Passmark GPU Compute scores 2,812, and Geekbench OpenCL hits 32,011. However, its DirectX scores are low in absolute terms: Passmark DirectX 9 scores 93, DirectX 10 scores 54, DirectX 11 scores 70, and DirectX 12 scores 30. The 3DMark Steel Nomad DX12 score of 176 reinforces that modern DirectX 12 gaming is not this card's strongest area, despite its compute prowess.

The NVIDIA GeForce 840M has far fewer recorded benchmarks, only two in the database: Geekbench OpenCL at 5,764 and Geekbench Vulkan at 4,880. Both are lower than the RX 6400's corresponding scores, and the 840M has no recorded Passmark or 3DMark results for comparison. The data does not show any test where the 840M beats the RX 6400. The head-to-head table records 2 wins for the RX 6400 and 0 for the 840M.

The RX 6400's nearest rivals in the database include the NVIDIA GeForce GTX 770M at an average score of 6,000 (0% delta), the NVIDIA RTX PRO 6000 Blackwell Server at 5,996 (0.1% ahead of the RX 6400), the AMD FirePro W4100 at 5,987 (0.2% ahead), and the NVIDIA Quadro K4000M at 5,986 (0.3% ahead). This cluster shows that the RX 6400 sits right at a performance tier boundary, effectively trading blows with those older or workstation-oriented cards. The 840M's nearest rivals include the NVIDIA GeForce 930A at 5,317 (0.1% ahead of the 840M), the NVIDIA GeForce GTX 980M at 5,308 (0.3% ahead), the AMD Radeon R7 M445 at 5,358 (0.7% behind the 840M), and the NVIDIA GeForce 940M at 5,284 (0.7% ahead). The 840M is therefore grouped with low-end mobile parts, while the RX 6400 is grouped with mid-range parts from earlier generations.

FAQ

Q: Which GPU is faster in Geekbench OpenCL?

A: The AMD Radeon RX 6400 scores 32,011 in Geekbench OpenCL, compared to 5,764 for the NVIDIA GeForce 840M. That is a 455.4% advantage for the RX 6400.

Q: How do the two cards compare in Geekbench Vulkan?

A: The RX 6400 scores 16,372 in Geekbench Vulkan, while the 840M scores 4,880. The RX 6400 leads by 235.5%.

Q: Which GPU has the higher average benchmark score?

A: The RX 6400 has an average benchmark score of 6,001, while the 840M averages 5,322.

Q: What are the percentile rankings of each card?

A: The RX 6400 is at the 35th percentile of all GPUs in the database, and the 840M is at the 31st percentile.

Q: Does the 840M win any recorded benchmark against the RX 6400?

A: No. The head-to-head data records 2 wins for the RX 6400 and 0 wins for the 840M across the tests they share.

Q: How does each card compare to its nearest rivals?

A: The RX 6400 is within 0.3% of the NVIDIA GeForce GTX 770M, RTX PRO 6000 Blackwell Server, AMD FirePro W4100, and NVIDIA Quadro K4000M in average score. The 840M is within 0.7% of the NVIDIA GeForce 930A, GTX 980M, AMD Radeon R7 M445, and NVIDIA GeForce 940M.

Architecture Differences

The two GPUs come from fundamentally different architectural generations. The AMD Radeon RX 6400 uses the RDNA 2.0 architecture, built on the Navi 24 chip, and belongs to the Navi II (RX 6000) generation. The NVIDIA GeForce 840M uses the Maxwell architecture, built on the GM108S chip, and belongs to the GeForce 800M generation. This is an eight-year gap in release timing, with the RX 6400 launching in January 2022 and the 840M launching in March 2014.

The manufacturing process is a major differentiator. The RX 6400 is fabricated on a 6 nm process at TSMC, while the 840M uses a 28 nm process, also at TSMC. The transistor counts reflect the process gap: the RX 6400 packs 5,400 million transistors on a 107 mm² die, for a transistor density of 50.5 million per mm². The 840M has 1,020 million transistors on a 77 mm² die, for a density of 13.2 million per mm². The RX 6400 nearly quadruples the transistor count on a die that is only 39% larger in area.

The memory subsystems are entirely different in kind. The RX 6400 uses 4 GB of GDDR6 memory on a 64-bit bus, delivering 128.0 GB/s of bandwidth. The 840M uses 2 GB of DDR3 memory on a 64-bit bus, delivering only 16.02 GB/s. That is an 8x difference in memory bandwidth, which directly impacts texture-heavy and high-resolution workloads.

The compute architectures differ in their feature sets. The RX 6400 has 768 shading units, 48 texture mapping units, and 32 render output units, plus 12 ray tracing cores. The 840M has 384 shading units, 16 TMUs, and 8 ROPs, with no ray tracing cores. The RX 6400 supports DirectX 12 Ultimate (12_2), while the 840M supports DirectX 12 (11_0), a lower feature level. Both support OpenGL 4.6 and Vulkan 1.4.

Clock speeds also differ substantially. The RX 6400 has a base clock of 1923 MHz, a boost clock of 2321 MHz, and a game clock of 2039 MHz, with memory running at 2000 MHz (16 Gbps effective). The 840M has a base clock of 1029 MHz and a boost clock of 1124 MHz, with memory at 1001 MHz (2 Gbps effective). The RX 6400's boost clock is more than double the 840M's.

The bus interfaces differ as well: the RX 6400 uses PCIe 4.0 x4, while the 840M uses PCIe 3.0 x8. The RX 6400 is a single-slot card with display outputs of 1x HDMI 2.1 and 1x DisplayPort 1.4a, while the 840M is an integrated GPU with outputs described as "Portable Device Dependent." The 840M is an IGP, meaning it is built for laptops and uses system-dependent display routing, while the RX 6400 is a discrete card.

Specification Differences

The two GPUs differ across nearly every specification field. The RX 6400 is part of the Radeon RX 6000 series, while the 840M has no series designation in the database. The RX 6400 is manufactured by AMD; the 840M by NVIDIA.

The process node differs: 6 nm for the RX 6400 versus 28 nm for the 840M. The RX 6400 has 5,400 million transistors on a 107 mm² die, while the 840M has 1,020 million transistors on a 77 mm² die. Transistor density is 50.5M per mm² for the RX 6400 versus 13.2M per mm² for the 840M.

Memory capacity is 4 GB of GDDR6 for the RX 6400 versus 2 GB of DDR3 for the 840M. Both use a 64-bit bus, but bandwidth is 128.0 GB/s versus 16.02 GB/s. The RX 6400 has 768 shading units, 48 TMUs, 32 ROPs, and 12 ray tracing cores; the 840M has 384 shading units, 16 TMUs, and 8 ROPs, with no ray tracing cores.

Pixel rate is 74.27 GPixel/s for the RX 6400 versus 8.992 GPixel/s for the 840M. Texture rate is 111.4 GTexel/s versus 17.98 GTexel/s. FP32 performance is 3.565 TFLOPS versus 863.2 GFLOPS. The RX 6400 also has FP16 performance of 7.130 TFLOPS (2:1), while the 840M has no recorded FP16 figure.

Power draw is 53 W for the RX 6400 versus 33 W for the 840M. The RX 6400 is single-slot with no power connectors and a suggested PSU of 250 W; the 840M is an IGP with no power connectors and no suggested PSU. The RX 6400 uses PCIe 4.0 x4, while the 840M uses PCIe 3.0 x8. The RX 6400 has 1x HDMI 2.1 and 1x DisplayPort 1.4a outputs; the 840M has "Portable Device Dependent" outputs. The RX 6400 supports DirectX 12 Ultimate (12_2); the 840M supports DirectX 12 (11_0). Both support OpenGL 4.6 and Vulkan 1.4. The RX 6400 has a launch MSRP of 159 USD; the 840M has no recorded launch MSRP. Both are end-of-life products.

Where Each One Wins

The RX 6400 wins in every category where data exists. In raw compute performance, its Geekbench OpenCL score of 32,011 is more than five times the 840M's 5,764. In Vulkan, its 16,372 is more than three times the 840M's 4,880. The RX 6400 also has substantially more memory bandwidth, more shading units, more TMUs, more ROPs, and ray tracing support, all of which point to better performance in modern workloads.

The RX 6400 is the better choice for any task that involves compute acceleration, modern API support, or higher-resolution textures. Its 4 GB of GDDR6 memory and 128.0 GB/s bandwidth make it viable for games and applications that require more than 2 GB of VRAM. Its DirectX 12 Ultimate support means it can handle feature-level 12_2 workloads, while the 840M is limited to DirectX 12 (11_0). Its PCIe 4.0 x4 interface is newer than the 840M's PCIe 3.0 x8.

The 840M has one advantage: power consumption. At 33 W, it draws 20 W less than the RX 6400's 53 W. For an integrated GPU in a laptop, that lower power draw is relevant, but it comes with a massive performance penalty. The 840M also has no recorded wins in any benchmark against the RX 6400.

The RX 6400's nearest rival cluster, which includes the GTX 770M and RTX PRO 6000 Blackwell Server at essentially equal average scores, shows that it competes at a specific performance tier. The 840M's rival cluster, including the 930A, GTX 980M, R7 M445, and 940M, places it in a much lower tier. The RX 6400 is not just faster than the 840M; it is in a different performance class entirely.

The Verdict

The data supports only one conclusion: the AMD Radeon RX 6400 is the superior GPU in every measured benchmark. It wins both head-to-head tests, holds a higher average benchmark score, and sits at a higher percentile of all GPUs. The 455.4% OpenCL lead and 235.5% Vulkan lead are decisive margins that no other interpretation can overcome.

Anyone choosing between these two for a desktop system should select the RX 6400 without hesitation. It offers modern architecture, ray tracing cores, 4 GB of GDDR6 memory, and support for DirectX 12 Ultimate. Its 159 USD launch MSRP, while not a current price, places it in a different market segment than a laptop-integrated GPU.

The NVIDIA GeForce 840M is only preferable in one narrow scenario: a system where the 33 W power draw is a hard constraint and the workload is light enough that the performance gap does not matter. For any compute, gaming, or graphics workload of consequence, the RX 6400 is the clear choice. The recorded data shows 2 wins for the RX 6400 and 0 for the 840M, and the underlying specifications reinforce that result.