AMD Radeon R6 M255DX vs AMD Radeon R7 M340 Comparison

AMD Radeon R7 M340 and AMD Radeon R6 M255DX are both end-of-life mobile graphics solutions from AMD, but they belong to different generations and architectural families. The R7 M340 is a discrete part built on GCN 3.0, while the R6 M255DX is an integrated graphics processor (IGP) using the older GCN 1.0 architecture. The benchmark data shows a single head-to-head comparison, with the R7 M340 taking the win, but the full picture requires examining their respective positions against their nearest rivals to understand what these scores mean in context.

Head-to-Head Benchmarks

The only direct benchmark comparison available between these two GPUs is the Geekbench Vulkan test. In this test, the AMD Radeon R7 M340 scores 5193, while the AMD Radeon R6 M255DX scores 4867. This gives the R7 M340 a 6.7% advantage over the R6 M255DX. This is a meaningful but not overwhelming lead; it indicates that the R7 M340 is the faster part in Vulkan workloads, but the R6 M255DX is not dramatically far behind. The R7 M340 also has a Geekbench OpenCL score of 4932, which is not directly compared to the R6 M255DX, as the latter lacks a published OpenCL result in the data set. The average benchmark score for the R7 M340 is 5063, which is higher than the R6 M255DX’s average of 4867.

Looking at the R7 M340’s position, its average score of 5063 puts it at the 30th percentile of all GPUs. Its nearest rival is the AMD Radeon R7 240, which has an identical average score of 5063, showing a 0% delta. The R7 M340 is also just 0.6% ahead of the AMD FirePro W4170M (5034) and 0.9% ahead of the AMD Radeon R5 M430 (5018). It is 1.3% ahead of the AMD Radeon R7 Graphics (4998). This suggests the R7 M340 is a mid-pack performer, clustered tightly with several other entry-level parts.

The R6 M255DX, with its average score of 4867, sits at the 28th percentile of all GPUs. Its nearest rival is the NVIDIA GeForce GTS 450, which scores 4893, meaning the R6 M255DX is 0.5% behind that card. It is also 0.2% behind the NVIDIA GeForce GTX 560M (4855) and 0.5% behind the NVIDIA GeForce 940MX (4844). Interestingly, the R6 M255DX trails the NVIDIA GeForce RTX 5060 Ti 8 GB by 0.7%, though that modern card’s score of 4901 is surprisingly close, indicating the R6 M255DX is not entirely obsolete in raw compute terms. The data shows the R7 M340 wins the sole head-to-head test, with 1 win for the R7 M340 and 0 wins for the R6 M255DX.

Where Each One Wins

Based strictly on the benchmark data, the AMD Radeon R7 M340 wins in every category where a direct comparison exists. It has the higher Vulkan score (5193 vs 4867) and the higher average benchmark score (5063 vs 4867). The R7 M340 also has a published OpenCL score of 4932, which the R6 M255DX does not have, suggesting the R7 M340 is more thoroughly tested across different API workloads. The R7 M340’s wins are not just about raw performance; it also holds a higher percentile ranking (30th vs 28th), indicating it outperforms a slightly larger fraction of the GPU population.

The R6 M255DX does not win any benchmark in the data set, but its position is not without merit. It is an integrated part, meaning it shares system memory and has a "System Dependent" bandwidth, which is a different use case than a discrete card. Its nearest rivals include several NVIDIA discrete mobile parts like the GeForce 940MX and GTX 560M, and it is within 0.5% of their scores. This indicates that while the R6 M255DX is slower than the R7 M340, it is competitive with a range of entry-level discrete GPUs from the same era. The R6 M255DX’s score of 4867 is actually higher than the R7 M340’s OpenCL score of 4932, but since these are different tests, no direct comparison can be made. The data shows that the R7 M340 is the clear winner in the head-to-head, but the R6 M255DX is a capable integrated option that holds its own against several discrete rivals.

The Verdict

From the data, the AMD Radeon R7 M340 is the faster GPU. It wins the only head-to-head benchmark by 6.7% and has a higher average score. A user seeking maximum performance in Vulkan-based applications should choose the R7 M340. Its higher percentile ranking (30th vs 28th) also suggests it is the more capable part overall. The R7 M340’s OpenCL score of 4932, while not compared directly, indicates it supports a broader range of compute workloads, as the R6 M255DX lacks any OpenCL result in the data.

The AMD Radeon R6 M255DX, however, is not without its appeal. As an integrated GPU, it is designed for portability and low power consumption, though the data does not specify wattage or size. Its performance is close to several discrete NVIDIA parts like the GeForce 940MX (0.5% behind) and the GeForce GTX 560M (0.2% behind), showing it can handle similar workloads. A user who requires an IGP solution with no discrete card, and who is willing to accept a modest performance deficit, could select the R6 M255DX. The data shows no scenario where the R6 M255DX outscores the R7 M340, so for pure performance, the R7 M340 is the definitive choice. The R6 M255DX is for those who prioritize the integrated form factor over raw speed.

FAQ

Q: Which GPU is faster in the Geekbench Vulkan test?

A: The AMD Radeon R7 M340 scores 5193, while the AMD Radeon R6 M255DX scores 4867, giving the R7 M340 a 6.7% lead.

Q: Does the R6 M255DX have any benchmark win over the R7 M340?

A: No. The data shows the R7 M340 has 1 win and the R6 M255DX has 0 wins in the head-to-head comparison.

Q: What is the average benchmark score for each GPU?

A: The R7 M340 has an average score of 5063, while the R6 M255DX has an average score of 4867.

Q: How does the R7 M340 compare to its nearest rival, the AMD Radeon R7 240?

A: The R7 M340 and the AMD Radeon R7 240 have identical average scores of 5063, showing a 0% delta.

Q: What is the percentile ranking of the R6 M255DX against all GPUs?

A: The R6 M255DX is at the 28th percentile of all GPUs, while the R7 M340 is at the 30th percentile.

Q: Does the R6 M255DX have an OpenCL benchmark score?

A: No, the data set only includes a Geekbench Vulkan score of 4867 for the R6 M255DX. The R7 M340 has both a Vulkan score (5193) and an OpenCL score (4932).

Architecture Differences

The two GPUs are built on different generations of AMD’s Graphics Core Next (GCN) architecture. The AMD Radeon R7 M340 uses GCN 3.0 and is based on the Meso chip, which contains 1,550 million transistors on a 125 mm² die. The AMD Radeon R6 M255DX uses the older GCN 1.0 architecture and is based on the Jet chip, which has 690 million transistors on a 56 mm² die. Both are manufactured on a 28 nm process by TSMC, with nearly identical transistor densities of 12.4M / mm² for the R7 M340 and 12.3M / mm² for the R6 M255DX. The R7 M340 is a discrete GPU with its own 2 GB of DDR3 memory on a 64-bit bus, while the R6 M255DX is an integrated GPU that shares system memory, with its bandwidth described as "System Dependent." The R7 M340 is part of the "Gem System (R7 M300)" generation, while the R6 M255DX belongs to the "Gem System Hybrid (Rx M200)" generation, indicating a different product line positioning.

The R7 M340 has a base clock of 943 MHz and a boost clock of 1021 MHz, while the R6 M255DX runs at a lower base clock of 780 MHz and a boost clock of 855 MHz. Both GPUs have the same number of shading units (320), texture mapping units (20), and render output units (8). The R7 M340’s higher clocks result in a pixel rate of 8.168 GPixel/s and a texture rate of 20.42 GTexel/s, compared to the R6 M255DX’s 6.840 GPixel/s and 17.10 GTexel/s. The R7 M340 also achieves higher FP32 performance at 653.4 GFLOPS, with a 1:1 FP16 ratio, while the R6 M255DX delivers 547.2 GFLOPS and has no listed FP16 value. The R7 M340 supports DirectX 12 (12_0), while the R6 M255DX supports DirectX 12 (11_1), a slightly lower feature level. Both support OpenGL 4.6 and Vulkan 1.2.170.

Specification Differences

The most critical specification difference is the memory subsystem. The AMD Radeon R7 M340 has a dedicated 2 GB of DDR3 memory with a 64-bit bus width and a bandwidth of 16.00 GB/s, running at 1000 MHz (2 Gbps effective). The AMD Radeon R6 M255DX uses "System Shared" memory, with a "System Shared" type and bus width, and its bandwidth is "System Dependent." This means the R7 M340 has a fixed, dedicated memory pool, while the R6 M255DX relies on the host system’s RAM, which can vary. The R7 M340’s memory clock is specified, while the R6 M255DX has no dedicated memory clock.

Clock speeds also differ. The R7 M340 has a base clock of 943 MHz and a boost clock of 1021 MHz, while the R6 M255DX has a lower base clock of 780 MHz and a boost clock of 855 MHz. This directly impacts performance, as reflected in the pixel rate (8.168 vs 6.840 GPixel/s) and texture rate (20.42 vs 17.10 GTexel/s). The R7 M340’s FP32 throughput is 653.4 GFLOPS, which is higher than the R6 M255DX’s 547.2 GFLOPS. The R7 M340 also has a higher transistor count (1,550 million vs 690 million) and a larger die size (125 mm² vs 56 mm²). The bus interface differs, with the R7 M340 using PCIe 3.0 x8, while the R6 M255DX is an IGP with no external bus. The R6 M255DX is listed as having "Portable Device Dependent" display outputs, whereas the R7 M340 has no specific display outputs listed. The R7 M340 supports DirectX 12 (12_0), while the R6 M255DX supports DirectX 12 (11_1). Finally, the release dates differ, with the R6 M255DX released on January 6, 2014, and the R7 M340 released on May 4, 2015, though neither has a launch MSRP listed.