AMD Radeon R8 M445DX vs NVIDIA GeForce GT 645M Comparison

The AMD Radeon R8 M445DX and NVIDIA GeForce GT 645M are both end-of-life mobile graphics solutions, but they represent fundamentally different design philosophies. The R8 M445DX is a hybrid system part from the Rx M400 generation, leveraging GCN 3.0 architecture, while the GT 645M is a discrete Kepler-based chip from the GeForce 600M family. Benchmark data shows a single head-to-head result where the AMD part holds a decisive lead, yet the NVIDIA card counters with broader API support in other tests. This analysis breaks down where each part wins based strictly on the available facts.

Where Each One Wins

The data presents a clear split: the AMD Radeon R8 M445DX dominates in raw compute throughput as measured by Geekbench OpenCL, while the NVIDIA GeForce GT 645M demonstrates superior performance in graphics-oriented workloads. In the sole direct comparison, the R8 M445DX scores 4727 in Geekbench OpenCL, crushing the GT 645M’s 2680 in the same test — a 76.4% advantage. This massive delta indicates that the AMD part is the stronger choice for general-purpose compute tasks, likely benefiting from its GCN 3.0 architecture’s design for parallel workloads.

However, the GT 645M shows its strength in other benchmark arenas. It achieves 5679 in Geekbench Metal, a test the R8 M445DX does not appear in, and 4875 in Geekbench Vulkan. The AMD part has no listed results for either Metal or Vulkan, which suggests that NVIDIA’s card is the more versatile option for graphics-heavy applications that leverage those APIs. The GT 645M’s Vulkan score of 4875 actually exceeds the R8 M445DX’s OpenCL score of 4727, hinting that the NVIDIA part can produce higher raw scores when the workload aligns with its strengths.

The percentile rankings reinforce this nuanced picture. The R8 M445DX sits at the 27th percentile of all GPUs, while the GT 645M is just one point lower at the 26th percentile. Their average benchmark scores tell a similar story: the AMD card averages 4727, while the NVIDIA card averages 4411. The R8 M445DX edges ahead in average score by 7.2%, but the GT 645M’s ability to compete across multiple APIs means it is not simply outclassed — it is a matter of workload type.

Architecture Differences

The architectural gap between these two parts is substantial. The AMD Radeon R8 M445DX uses the Meso chip built on GCN 3.0, manufactured on a 28 nm process at TSMC. It packs 1,550 million transistors into a 125 mm² die, yielding a transistor density of 12.4 million per mm². The NVIDIA GeForce GT 645M, by contrast, employs the GK107 chip with Kepler architecture, also on TSMC’s 28 nm node, but with fewer resources: 1,270 million transistors on a 118 mm² die, resulting in 10.8 million transistors per mm².

Core configurations diverge significantly. The R8 M445DX fields 320 shading units, 20 texture mapping units, and 8 ROPs. The GT 645M counters with 384 shading units, 32 TMUs, and 16 ROPs. Despite having fewer shading units, the AMD part achieves a higher pixel rate of 8.168 GPixel/s versus the NVIDIA card’s 6.240 GPixel/s. The texture rate flips the other way: the GT 645M outputs 24.96 GTexel/s against the R8 M445DX’s 20.42 GTexel/s. Floating-point performance also favors AMD — 653.4 GFLOPS FP32 versus 599.0 GFLOPS for NVIDIA — with the R8 M445DX additionally supporting FP16 at a 1:1 ratio, a feature the GT 645M lacks entirely.

Memory configurations could not be more different. The R8 M445DX uses system shared memory, with size, type, bus width, and bandwidth all marked as dependent on the host system. The GT 645M features dedicated 2 GB of DDR3 memory on a 128-bit bus, delivering 28.80 GB/s of bandwidth. This gives the NVIDIA card a fixed memory advantage, though the AMD part’s shared memory approach can scale with system RAM. Clock speeds also differ: the R8 M445DX runs at a 780 MHz base and 1021 MHz boost, while the GT 645M operates at 709 MHz base and 780 MHz boost, with memory clocked at 900 MHz (1800 Mbps effective).

API support is another dividing line. Both support DirectX 12 and OpenGL 4.6, but the R8 M445DX lists DirectX 12 at feature level 12_0, whereas the GT 645M is limited to 11_0. Vulkan support is present on both, but the NVIDIA card’s version 1.2.175 is marginally newer than AMD’s 1.2.170. The GT 645M also adds Metal support, which the AMD part does not list. Power and interface details differ: the GT 645M has a 32 W TDP and uses PCIe 3.0 x16, while the R8 M445DX is an IGP with no listed TDP and a bus interface marked simply as IGP.

The Verdict

The benchmark results indicate that the AMD Radeon R8 M445DX is the superior choice for compute-intensive workloads, particularly those that stress OpenCL. Its 76.4% lead over the GT 645M in Geekbench OpenCL is overwhelming, and its higher FP32 throughput and FP16 support make it a more capable part for general-purpose processing. The R8 M445DX also holds a slight edge in average score (4727 vs 4411) and percentile rank (27th vs 26th).

The NVIDIA GeForce GT 645M, however, is the better option for graphics-oriented tasks that leverage Metal or Vulkan APIs. Its Geekbench Metal score of 5679 and Vulkan score of 4875 demonstrate strong performance in those specific environments, which the AMD part cannot match due to lack of support. The dedicated 2 GB DDR3 memory with fixed bandwidth also provides predictable performance, unlike the R8 M445DX’s system-dependent shared memory.

For users prioritizing raw compute or running OpenCL-heavy applications, the AMD Radeon R8 M445DX is the clear pick. For those needing broader API coverage, particularly Metal on macOS or Vulkan, the NVIDIA GeForce GT 645M is more practical. The data does not support a universal winner — it supports a workload-specific choice.

FAQ

Q: Which GPU has the higher Geekbench OpenCL score?

A: The AMD Radeon R8 M445DX scores 4727, which is 76.4% higher than the NVIDIA GeForce GT 645M’s 2680 in the same test.

Q: Does the NVIDIA GeForce GT 645M support Metal?

A: Yes, the GT 645M has a Geekbench Metal score of 5679. The AMD Radeon R8 M445DX has no listed Metal benchmark.

Q: What is the memory configuration of each GPU?

A: The NVIDIA GeForce GT 645M has 2 GB of DDR3 memory on a 128-bit bus with 28.80 GB/s bandwidth. The AMD Radeon R8 M445DX uses system shared memory with bandwidth dependent on the host system.

Q: Which GPU has more shading units?

A: The NVIDIA GeForce GT 645M has 384 shading units, compared to 320 on the AMD Radeon R8 M445DX.

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

A: The AMD Radeon R8 M445DX averages 4727, while the NVIDIA GeForce GT 645M averages 4411. The AMD part holds a 7.2% advantage in average score.

Q: Which GPU supports FP16 computation?

A: The AMD Radeon R8 M445DX supports FP16 at a 1:1 ratio with FP32. The NVIDIA GeForce GT 645M has no listed FP16 support.

Head-to-Head Benchmarks

The single direct comparison available is Geekbench OpenCL, and it is a decisive victory for AMD. The Radeon R8 M445DX delivers 4727 points against the GeForce GT 645M’s 2680, a 76.4% margin. This result aligns with the architectural data: the AMD part produces 653.4 GFLOPS of FP32 performance versus 599.0 GFLOPS for NVIDIA, and its higher boost clock of 1021 MHz versus 780 MHz contributes to the gap. The R8 M445DX’s pixel rate of 8.168 GPixel/s also outpaces the GT 645M’s 6.240 GPixel/s, reinforcing its compute advantage.

The NVIDIA card’s biggest wins come outside the direct comparison. Its Geekbench Vulkan score of 4875 is 7.3% higher than the AMD part’s OpenCL score of 4727, though these are different tests. More impressively, the GT 645M achieves 5679 in Geekbench Metal, which stands as the highest single benchmark score between the two GPUs. The GT 645M’s texture rate of 24.96 GTexel/s exceeds the R8 M445DX’s 20.42 GTexel/s by 22.2%, indicating better texture-processing capability despite lower raw compute.

The R8 M445DX counters with its FP16 capability, offering 653.4 GFLOPS of half-precision performance, a feature entirely absent from the GT 645M. The AMD part also has a higher transistor density at 12.4 million per mm² versus 10.8 million per mm², suggesting more efficient use of die area. In the OpenCL test specifically, the R8 M445DX’s 76.4% lead over the GT 645M is the defining statistic — it dwarfs the 1.3% gap between the R8 M445DX and the RTX 3080 12 GB in the nearest rivals list, showing that the AMD part is competitive in compute despite its modest positioning. The GT 645M, meanwhile, sits just 0.5% ahead of the GeForce 930M and 1.8% ahead of the RTX 4070 GDDR6 in its rival list, indicating it holds its own in a narrow band of performance.