AMD Radeon R5 M255 vs NVIDIA GeForce 840M Comparison

The NVIDIA GeForce 840M and AMD Radeon R5 M255 are both end-of-life mobile graphics solutions from the 2014 era, aimed at thin-and-light laptops. The database places the NVIDIA part at the 31st percentile of all GPUs, while the AMD part sits at the 28th, indicating that both are near the bottom of the performance spectrum. The average benchmark score for the GeForce 840M is 5322, while the Radeon R5 M255 averages 4788. This difference of roughly 11% in aggregate performance is the first clear sign that the two are not equal, but the individual tests tell a more nuanced story.

Head-to-Head Benchmarks

The most decisive result in the recorded data comes from the Geekbench OpenCL test. Here, the NVIDIA GeForce 840M scores 5764, while the AMD Radeon R5 M255 scores 4650. That is a 24% advantage for the NVIDIA part, and it is the largest performance gap in either direction between these two products. For compute workloads that rely on OpenCL, the 840M is clearly the stronger option. The margin is substantial enough that users running general-purpose GPU tasks or OpenCL-accelerated applications would notice the difference immediately.

The Vulkan test flips the result, though by a much smaller margin. The AMD Radeon R5 M255 scores 4925, while the NVIDIA GeForce 840M scores 4880. The delta is only 0.9%, which is within the range of run-to-run variance in most benchmark scenarios. In practical terms, the two are effectively tied in Vulkan performance, with the AMD part holding a razor-thin lead. This means that in modern graphics APIs, neither card has a meaningful edge over the other. The raw numbers suggest that the 840M wins the compute-heavy OpenCL test decisively, while the R5 M255 wins the Vulkan test only by a hair.

Looking at the nearest rivals in the database provides context for these scores. The GeForce 840M, with its average of 5322, sits close to the NVIDIA GeForce 930A, which averages 5317, a difference of just 0.1%. It is also within 0.3% of the NVIDIA GeForce GTX 980M, which averages 5308, and 0.7% ahead of the NVIDIA GeForce 940M at 5284. The only rival that beats it in the recorded list is the AMD Radeon R7 M445, which averages 5358, a 0.7% advantage. These are all extremely tight margins, indicating that the 840M sits in a crowded performance tier where small differences separate products.

The AMD Radeon R5 M255, with its average of 4788, is grouped with a different set of rivals. It is within 0.1% of the NVIDIA GeForce RTX 3080 12 GB, which averages 4791, a surprising pairing that reflects the averaging method rather than real-world equivalence. More relevantly, it is 0.8% ahead of the AMD Radeon R5 M335 at 4752, and 1.3% ahead of the AMD Radeon R8 M445DX at 4727. The NVIDIA GeForce 940MX averages 4844, which is 1.2% ahead of the R5 M255. The pattern here is that the R5 M255 is grouped with other low-end mobile parts, and its closest comparisons are all within a couple of percentage points.

Where Each One Wins

The NVIDIA GeForce 840M wins the OpenCL benchmark outright, and that is its primary strength in this comparison. With a 24% lead over the R5 M255 in this test, the 840M is the better choice for any workload that leverages OpenCL compute. This includes tasks such as video encoding, physics simulations, and certain rendering pipelines that use OpenCL as their backend. The 840M also has a higher FP32 throughput in the recorded specifications, at 863.2 GFLOPS compared to 721.9 GFLOPS for the AMD part. That compute advantage aligns with its OpenCL performance and reinforces the idea that the 840M is the more capable compute-oriented chip.

The AMD Radeon R5 M255 wins the Vulkan test, but the margin is so small that it is hard to call it a genuine victory. A 0.9% lead in Vulkan is negligible in real-world usage. However, the direction of the result matters. The R5 M255 supports DirectX 12 at feature level 12_0, while the GeForce 840M supports DirectX 12 at feature level 11_0. This means the AMD part is technically more aligned with modern graphics API feature sets, even if its raw performance in Vulkan is nearly identical to the NVIDIA part. For users who prioritize having the latest API feature support, the R5 M255 has a slight edge on paper.

The texture rate favors the AMD part as well. The R5 M255 has a texture fill rate of 22.56 GTexel/s, compared to 17.98 GTexel/s for the GeForce 840M. This is a 25% advantage for AMD in raw texture throughput, which can help in texture-heavy scenes. However, the pixel rate tells the opposite story. The 840M delivers 8.992 GPixel/s, while the R5 M255 delivers 7.520 GPixel/s, a 20% advantage for NVIDIA. These two metrics often trade off depending on the balance of TMUs and ROPs in a chip, and in this case, each card has a clear lead in one of them.

The Verdict

The data points to the NVIDIA GeForce 840M as the stronger overall product. Its 11% higher average benchmark score, combined with a 24% lead in OpenCL, makes it the safer choice for most users. The only recorded test where the AMD Radeon R5 M255 comes out ahead is Vulkan, and the margin there is just 0.9%, which is not enough to overcome the NVIDIA part's advantages elsewhere. If a user is choosing between these two for a laptop, the 840M is the one to pick for compute-heavy tasks and general performance.

The AMD Radeon R5 M255 is not without its merits. Its 128-bit memory bus provides 32.00 GB/s of bandwidth, double the 16.02 GB/s of the GeForce 840M, which has a 64-bit bus. This memory bandwidth advantage can help in bandwidth-sensitive scenarios, though the 840M's higher core clock speeds and compute throughput offset much of that in the recorded benchmarks. The R5 M255 also supports DirectX 12 feature level 12_0, which is a more modern API target than the 840M's 11_0. For users who specifically need that feature level, the AMD part is the only option between the two.

For gamers, the recorded data does not suggest either card is a strong choice. Both sit below the 31st percentile of all GPUs, and their average scores place them in the low-end tier of mobile graphics. The 840M is the better of the two, but neither will handle demanding modern titles at high settings. For casual use, light gaming, or GPU-accelerated compute, the 840M is the clear pick. For users who value the slightly newer DirectX feature set or the doubled memory bandwidth, the R5 M255 is a defensible alternative, but the benchmark data does not support choosing it on raw performance grounds.

FAQ

Q: Which GPU has the higher average benchmark score?

A: The NVIDIA GeForce 840M has an average benchmark score of 5322, while the AMD Radeon R5 M255 averages 4788.

Q: How large is the OpenCL performance gap between the two?

A: The NVIDIA GeForce 840M scores 5764 in Geekbench OpenCL, while the AMD Radeon R5 M255 scores 4650, giving the 840M a 24% advantage.

Q: Does the AMD Radeon R5 M255 win any benchmark?

A: Yes, it wins the Geekbench Vulkan test with a score of 4925 versus 4880 for the NVIDIA GeForce 840M, a margin of 0.9%.

Q: What is the memory bandwidth difference?

A: The AMD Radeon R5 M255 has 32.00 GB/s of bandwidth from its 128-bit bus, while the NVIDIA GeForce 840M has 16.02 GB/s from a 64-bit bus.

Q: Which GPU has higher FP32 compute throughput?

A: The NVIDIA GeForce 840M delivers 863.2 GFLOPS, compared to 721.9 GFLOPS for the AMD Radeon R5 M255.

Q: Do both GPUs support the same DirectX version?

A: No. The AMD Radeon R5 M255 supports DirectX 12 at feature level 12_0, while the NVIDIA GeForce 840M supports DirectX 12 at feature level 11_0.

Architecture Differences

The NVIDIA GeForce 840M is built on the Maxwell architecture, using the GM108S chip manufactured on a 28 nm process at TSMC. The die contains 1,020 million transistors on a 77 mm² die, resulting in a transistor density of 13.2 million transistors per square millimeter. The AMD Radeon R5 M255 uses the GCN 3.0 architecture with the Topaz chip, also on a 28 nm TSMC process. Its die is larger at 125 mm² and contains 1,550 million transistors, giving it a slightly lower density of 12.4 million transistors per square millimeter. The higher transistor count on the AMD side does not translate into better benchmark performance, as the recorded scores show.

The two GPUs have the same number of shading units at 384, but the AMD part has more texture mapping units. The R5 M255 has 24 TMUs, while the GeForce 840M has 16. Both have 8 ROPs. The extra TMUs give the AMD part a higher texture fill rate of 22.56 GTexel/s versus 17.98 GTexel/s, but the NVIDIA part compensates with higher clock speeds. The 840M runs at a base clock of 1029 MHz and a boost clock of 1124 MHz, while the R5 M255 runs at 925 MHz base and 940 MHz boost. That clock advantage helps the 840M achieve a higher pixel rate of 8.992 GPixel/s compared to 7.520 GPixel/s.

The memory subsystems are notably different. The GeForce 840M uses a 64-bit bus with 2 GB of DDR3 memory at 1001 MHz, delivering 16.02 GB/s of bandwidth. The Radeon R5 M255 uses a 128-bit bus with 2 GB of DDR3 at 1000 MHz, delivering 32.00 GB/s. Both have the same memory size and type, but the AMD part has double the bus width and bandwidth. The AMD part also has a Vulkan version of 1.2.170, while the NVIDIA part lists Vulkan 1.4 support. Both support OpenGL 4.6. The NVIDIA part has a TDP of 33 W and is marked as an IGP with no power connectors, while the AMD part has no TDP, slot width, or power connector data recorded.

Specification Differences

The clock speeds are a clear differentiator. The NVIDIA GeForce 840M has a base clock of 1029 MHz and a boost clock of 1124 MHz, while the AMD Radeon R5 M255 has a base clock of 925 MHz and a boost clock of 940 MHz. The memory clock is nearly identical, at 1001 MHz for the NVIDIA part and 1000 MHz for the AMD part, both yielding 2 Gbps effective. The memory bus width differs significantly: 64 bits for the 840M versus 128 bits for the R5 M255. This leads to the bandwidth difference of 16.02 GB/s versus 32.00 GB/s.

The compute metrics differ as well. The GeForce 840M has an FP32 throughput of 863.2 GFLOPS, while the Radeon R5 M255 has 721.9 GFLOPS. The AMD part also lists an FP16 throughput of 721.9 GFLOPS with a 1:1 ratio to FP32, while the NVIDIA part has no FP16 data recorded. The pixel rate is 8.992 GPixel/s for the 840M and 7.520 GPixel/s for the R5 M255. The texture rate is 17.98 GTexel/s for the 840M and 22.56 GTexel/s for the R5 M255.

The API support differs in the DirectX version. The NVIDIA part supports DirectX 12 at feature level 11_0, while the AMD part supports DirectX 12 at feature level 12_0. The Vulkan version is 1.4 for NVIDIA and 1.2.170 for AMD. Both support OpenGL 4.6. The die details differ, with the 840M using a 77 mm² die with 1,020 million transistors and the R5 M255 using a 125 mm² die with 1,550 million transistors. The release dates are also different, with the 840M released on 2014-03-11 and the R5 M255 on 2014-10-11. The NVIDIA part has a recorded TDP of 33 W and a slot width of IGP, while the AMD part has no such data recorded.