AMD Radeon R7 M340 vs NVIDIA GeForce GT 645M Comparison

FAQ

Q: Which GPU has the higher average benchmark score in the database?

A: The AMD Radeon R7 M340 records an average benchmark score of 5063, which is higher than the NVIDIA GeForce GT 645M's average of 4411. The AMD part also sits at the 30th percentile among all GPUs, while the NVIDIA part sits at the 26th percentile.

Q: How do these two GPUs compare in the OpenCL benchmark?

A: The AMD Radeon R7 M340 scores 4932 in Geekbench OpenCL, while the NVIDIA GeForce GT 645M scores 2680. This gives AMD a decisive 84% lead in that test.

Q: Is the NVIDIA GeForce GT 645M competitive in any benchmark?

A: In the Geekbench Vulkan test, the NVIDIA card scores 4875, which is much closer to the AMD's 5193. The delta is only 6.5% in favor of AMD, making Vulkan the NVIDIA card's best showing.

Q: What memory configuration does each GPU use?

A: Both cards use 2 GB of DDR3 memory. However, the AMD Radeon R7 M340 uses a 64-bit bus with 16.00 GB/s bandwidth, while the NVIDIA GeForce GT 645M uses a 128-bit bus with 28.80 GB/s bandwidth.

Q: Which GPU has the higher transistor density?

A: The AMD Radeon R7 M340, built on TSMC's 28 nm process, has a transistor density of 12.4M per mm². The NVIDIA GeForce GT 645M, also on a 28 nm TSMC process, has a density of 10.8M per mm².

Q: What are the architecture generations for these two products?

A: The AMD Radeon R7 M340 is based on the GCN 3.0 architecture from the Gem System (R7 M300) generation. The NVIDIA GeForce GT 645M is based on the Kepler architecture from the GeForce 600M generation.

Architecture Differences

The AMD Radeon R7 M340 uses the Meso chip with GCN 3.0 architecture, while the NVIDIA GeForce GT 645M uses the GK107 chip with Kepler architecture. Both are manufactured by TSMC on a 28 nm process, but the AMD chip packs more transistors: 1,550 million versus 1,270 million. The AMD die is also slightly larger at 125 mm² compared to 118 mm². This translates to a higher transistor density for AMD at 12.4M per mm² versus 10.8M per mm².

The compute layouts differ significantly. The AMD card has 320 shading units, 20 texture mapping units, and 8 raster operation units. The NVIDIA card has more of each: 384 shading units, 32 TMUs, and 16 ROPs. Despite having fewer ROPs, the AMD card achieves a higher pixel rate of 8.168 GPixel/s compared to 6.240 GPixel/s on the NVIDIA part. The texture rates are closer, with NVIDIA's 24.96 GTexel/s edging out AMD's 20.42 GTexel/s.

Clock speeds show a clear divergence. The AMD card runs at a base clock of 943 MHz with a boost of 1021 MHz, while the NVIDIA card runs much lower at 709 MHz base and 780 MHz boost. The memory clocks also differ, with AMD at 1000 MHz (2 Gbps effective) and NVIDIA at 900 MHz (1800 Mbps effective). The bus widths differ as well: AMD uses a 64-bit interface, NVIDIA uses 128-bit. This gives NVIDIA a notable bandwidth advantage at 28.80 GB/s versus 16.00 GB/s.

The API support reveals generational differences. AMD supports DirectX 12 (12_0), while NVIDIA only reaches DirectX 12 (11_0). Both support OpenGL 4.6 and Vulkan, with NVIDIA carrying a slightly newer Vulkan version (1.2.175 versus 1.2.170). The bus interface also differs: AMD uses PCIe 3.0 x8, NVIDIA uses PCIe 3.0 x16. The NVIDIA card is rated at 32 W TDP and uses no power connectors, but the AMD card has no recorded TDP in the database.

The Verdict

The data points to the AMD Radeon R7 M340 as the stronger performer overall. Its average benchmark score of 5063 is roughly 15% higher than the GT 645M's 4411, and it wins both head-to-head benchmark tests. The AMD card also carries a higher percentile ranking at 30 versus 26. For users running OpenCL workloads, the choice is clear: the R7 M340 leads by an 84% margin. For Vulkan workloads, the gap narrows to 6.5%, but the AMD card still comes out ahead.

The NVIDIA GeForce GT 645M still has a role. Its 128-bit memory bus provides 28.80 GB/s of bandwidth, which is 80% higher than the AMD card's 16.00 GB/s. It also has more shading units, TMUs, and ROPs. In scenarios that are heavily bandwidth-bound or that favor raw geometry throughput, the GT 645M may hold its own despite the overall score deficit. Its lower TDP of 32 W also suggests it may fit into more power-constrained designs, though the AMD card's power draw is not recorded in the database.

For most general-purpose computing and gaming workloads measured by these benchmarks, the AMD Radeon R7 M340 is the safer pick. The Vulkan result shows that NVIDIA is not far behind, but the OpenCL gap is too large to ignore.

Specification Differences

| Specification | AMD Radeon R7 M340 | NVIDIA GeForce GT 645M |

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

| Architecture | GCN 3.0 | Kepler |

| Chip | Meso | GK107 |

| Generation | Gem System (R7 M300) | GeForce 600M |

| Transistors | 1,550 million | 1,270 million |

| Die Size | 125 mm² | 118 mm² |

| Transistor Density | 12.4M / mm² | 10.8M / mm² |

| Base Clock | 943 MHz | 709 MHz |

| Boost Clock | 1021 MHz | 780 MHz |

| Memory Clock | 1000 MHz (2 Gbps effective) | 900 MHz (1800 Mbps effective) |

| Memory Bus Width | 64 bit | 128 bit |

| Memory Bandwidth | 16.00 GB/s | 28.80 GB/s |

| Shading Units | 320 | 384 |

| TMUs | 20 | 32 |

| ROPs | 8 | 16 |

| Pixel Rate | 8.168 GPixel/s | 6.240 GPixel/s |

| Texture Rate | 20.42 GTexel/s | 24.96 GTexel/s |

| FP32 | 653.4 GFLOPS | 599.0 GFLOPS |

| FP16 | 653.4 GFLOPS (1:1) | Not recorded |

| TDP | Not recorded | 32 W |

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

| DirectX Support | 12 (12_0) | 12 (11_0) |

| Vulkan Version | 1.2.170 | 1.2.175 |

| Release Date | 2015-05-04 | 2012-09-30 |

Head-to-Head Benchmarks

The database records two direct head-to-head comparisons between these GPUs. In Geekbench OpenCL, the AMD Radeon R7 M340 scores 4932 against the NVIDIA GeForce GT 645M's 2680. That is an 84% delta, the single largest performance gap in this comparison. The AMD card's FP32 output of 653.4 GFLOPS, combined with its higher clocks, explains much of this advantage. The NVIDIA card's FP32 figure is lower at 599.0 GFLOPS, and its base clock of 709 MHz trails the AMD's 943 MHz by a wide margin.

In Geekbench Vulkan, the results are much tighter. The AMD card scores 5193, and the NVIDIA card scores 4875. The delta shrinks to 6.5%. This suggests that under the Vulkan API, the NVIDIA Kepler architecture closes most of the gap. The NVIDIA card's additional shading units and wider memory bus likely help in this workload. Still, the AMD card maintains the lead, and the overall wins column shows AMD ahead at 2 wins versus 0 for NVIDIA.

Where Each One Wins

The AMD Radeon R7 M340 wins decisively in OpenCL compute workloads. The 84% lead over the GT 645M makes it the clear choice for general-purpose GPU computing tasks that rely on OpenCL. Its higher clock speeds, superior FP32 throughput, and newer GCN 3.0 architecture all contribute. The card also wins the Vulkan test, though by a smaller 6.5% margin. For users who prioritize compute performance across both APIs, the R7 M340 is the stronger option.

The NVIDIA GeForce GT 645M wins in the memory bandwidth department. Its 128-bit bus delivers 28.80 GB/s versus 16.00 GB/s for the AMD card. It also has more shading units (384 versus 320), more TMUs (32 versus 20), and more ROPs (16 versus 8). The texture rate is higher at 24.96 GTexel/s compared to 20.42 GTexel/s. For workloads that are bandwidth-limited or that benefit from higher geometry throughput, the GT 645M may perform relatively better than its average score suggests. Its lower TDP of 32 W is also an advantage in power-sensitive mobile designs.

The practical split is this: for compute-heavy tasks using OpenCL, the AMD Radeon R7 M340 is the clear winner. For Vulkan-based workloads, the AMD card still wins, but the margin is slim enough that the NVIDIA card's other strengths, such as memory bandwidth and lower power draw, could tip a system builder's decision. The recorded data shows AMD ahead in both head-to-head tests, but the NVIDIA card remains a viable option where its memory subsystem and power profile matter most.