GPU Comparison

The data is unambiguous: the AMD Radeon 550 is the overwhelmingly stronger performer in every directly comparable benchmark, while the NVIDIA GeForce GT 640 offers only architectural and API-level distinctions that do not translate into compute victories. In the two head-to-head tests available, the Radeon 550 dominates the GT 640 by margins exceeding 60 percent, cementing its place as the more capable GPU despite its lower overall percentile ranking.

Head-to-Head Benchmarks

The benchmark results show a decisive, one-sided contest. In Geekbench OpenCL, the AMD Radeon 550 scores 10,339 points, while the NVIDIA GeForce GT 640 manages just 3,736 points. This represents a 63.9 percent advantage for the Radeon 550. The margin is even larger in Geekbench Vulkan, where the Radeon 550 posts 11,257 points against the GT 640's 3,809 points, a 66.2 percent lead. These are not marginal wins; they are generational leaps in raw compute throughput. The GT 640 fails to claim a single victory across the entire head-to-head suite, and the data shows zero wins for NVIDIA.

The Radeon 550's advantage is consistent with its higher-level specifications. Its FP32 compute output is 1,211.4 GFLOPS, nearly double the GT 640's 692.7 GFLOPS. The texture rate tells a similar story: 37.86 GTexel/s for the Radeon 550 versus 28.86 GTexel/s for the GT 640. Pixel rate is where the gap becomes enormous, with the Radeon 550 achieving 18.93 GPixel/s compared to the GT 640's 7.216 GPixel/s, a 2.6x difference. The Radeon 550 also has superior memory bandwidth at 56.00 GB/s versus 28.51 GB/s, which directly feeds its compute and rendering performance. While the GT 640's average benchmark score is 3,210, the Radeon 550's is lower at 2,801, but this aggregate figure is skewed by the Radeon 550's inclusion of additional PassMark tests (DirectX 9, 10, 11, 12, G2D, G3D, and GPU Compute), where its scores are modest. In the pure Geekbench metrics that both cards share, the Radeon 550 is categorically superior.

Architecture Differences

The two GPUs come from different architectural eras and manufacturing processes. The NVIDIA GeForce GT 640 uses the GK107 chip based on the Kepler architecture, built on a 28 nm process at TSMC. It packs 1,270 million transistors into a 118 mm² die, yielding a transistor density of 10.8 million per square millimeter. The AMD Radeon 550, in contrast, uses the Lexa chip based on GCN 4.0 architecture, part of the Polaris (RX 500) generation, manufactured on a 14 nm process at GlobalFoundries. It contains 2,200 million transistors on a smaller 103 mm² die, achieving a much higher density of 21.4 million per square millimeter. The Radeon 550's newer node and denser design explain its superior performance per watt and per square millimeter.

Core configurations differ substantially. The GT 640 has 384 shading units, 32 texture mapping units (TMUs), and 16 raster output units (ROPs). The Radeon 550 raises this to 512 shading units, 32 TMUs, and 16 ROPs. The extra 128 shading units provide the Radeon 550 with a clear computational edge in parallel workloads. Memory systems also diverge: the GT 640 uses 2 GB of DDR3 on a 128-bit bus, while the Radeon 550 uses 2 GB of GDDR5 on a 64-bit bus. Despite the narrower bus, GDDR5's higher clock speed (1750 MHz versus 891 MHz) gives the Radeon 550 nearly double the bandwidth, 56.00 GB/s versus 28.51 GB/s. Clock speeds follow the same pattern: the GT 640 has no listed base or boost clock, while the Radeon 550 runs at 1100 MHz base and 1183 MHz boost.

API support is another differentiator. The GT 640 supports DirectX 12 (11_0), while the Radeon 550 supports DirectX 12 (12_0), a full feature-level advantage. Vulkan support also differs, with the GT 640 at version 1.2.175 and the Radeon 550 at version 1.3. Both support OpenGL 4.6. Display outputs favor the Radeon 550: it offers HDMI 2.0b and DisplayPort 1.4a, while the GT 640 is limited to HDMI 1.4a and DisplayPort 1.2. The Radeon 550 also supports FP16 compute at 1,211.4 GFLOPS (1:1 ratio with FP32), a capability the GT 640 lacks entirely. Power consumption is lower on the Radeon 550 (50 W TDP versus 65 W), despite its higher performance, reflecting the efficiency gains of the 14 nm process.

The Verdict

The data dictates a single conclusion: the AMD Radeon 550 is the superior GPU for any compute-intensive or modern API workload. It wins both head-to-head benchmarks by margins of 63.9 percent (OpenCL) and 66.2 percent (Vulkan). Its FP32 output is 74.9 percent higher than the GT 640's, and its pixel rate is more than 2.6 times greater. The Radeon 550 also offers newer DirectX 12 (12_0) and Vulkan 1.3 support, which the GT 640 cannot match. The GT 640's only "advantage" is its higher average benchmark score (3,210 versus 2,801), but this is an artifact of the Radeon 550's broader test suite, which includes weak PassMark DirectX scores (e.g., 7 in DirectX 10, 15 in DirectX 11). In every shared metric, the Radeon 550 wins.

Who should pick the GT 640? Only those constrained by legacy software or specific display output needs that favor its 128-bit bus and 1.5 percent higher rating among its nearest rivals (the GT 640 sits at the 20th percentile versus the Radeon 550's 18th). The GT 640's nearest rival, the NVIDIA Quadro P1000, is just 1.5 percent behind it, indicating a tight cluster of older low-end GPUs. The Radeon 550, by contrast, sits near the NVIDIA GeForce RTX 3060 Ti GDDR6X (0.2 percent delta), a much newer and more capable card, suggesting its performance profile is closer to modern mid-range parts. For anyone choosing between these two, the Radeon 550 is the only rational option based on benchmark data.

FAQ

Q: Which GPU has the higher Geekbench Vulkan score?

A: The AMD Radeon 550 scores 11,257 points, which is 66.2 percent higher than the NVIDIA GeForce GT 640's 3,809 points.

Q: How much faster is the AMD Radeon 550 in OpenCL compute?

A: The Radeon 550 scores 10,339 points versus the GT 640's 3,736 points, a 63.9 percent advantage.

Q: Do the two cards have the same memory bandwidth?

A: No. The GT 640 has 28.51 GB/s of bandwidth from DDR3 memory, while the Radeon 550 has 56.00 GB/s from GDDR5 memory, nearly double.

Q: Are there differences in API support?

A: Yes. The GT 640 supports DirectX 12 (11_0) and Vulkan 1.2.175, while the Radeon 550 supports DirectX 12 (12_0) and Vulkan 1.3. Both support OpenGL 4.6.

Q: Which card has a higher transistor count?

A: The AMD Radeon 550 has 2,200 million transistors, compared to 1,270 million for the NVIDIA GeForce GT 640. The Radeon 550's die is smaller (103 mm² versus 118 mm²) and uses a 14 nm process versus 28 nm.

Q: How do their power requirements compare?

A: The Radeon 550 has a 50 W TDP, while the GT 640 has a 65 W TDP. Both have a suggested PSU of 250 W and require no power connectors.

Where Each One Wins

The AMD Radeon 550 wins in every performance category that matters. It dominates in Geekbench OpenCL (10,339 vs 3,736) and Geekbench Vulkan (11,257 vs 3,809). It has higher FP32 compute (1,211.4 GFLOPS vs 692.7 GFLOPS), higher texture rate (37.86 GTexel/s vs 28.86 GTexel/s), and higher pixel rate (18.93 GPixel/s vs 7.216 GPixel/s). It also has more shading units (512 vs 384), double the memory bandwidth (56.00 GB/s vs 28.51 GB/s), and support for FP16 compute at 1,211.4 GFLOPS. Its 14 nm process and 21.4M/mm² transistor density give it an efficiency advantage, with lower TDP (50 W vs 65 W) despite higher performance. In terms of display outputs, the Radeon 550's HDMI 2.0b and DisplayPort 1.4a are newer standards than the GT 640's HDMI 1.4a and DisplayPort 1.2.

The NVIDIA GeForce GT 640's wins are limited to the abstract. It has a higher average benchmark score (3,210 vs 2,801) and a higher percentile ranking (20th vs 18th). Its 128-bit memory bus is wider than the Radeon 550's 64-bit bus, and its nearest rivals (e.g., Quadro P1000, 1.5 percent delta) are closer in performance, suggesting a more consistent low-end profile. It also uses a single-slot design versus the Radeon 550's dual-slot, which may matter in space-constrained systems. However, these are not performance wins; they are specification or form-factor distinctions. In any workload that leverages compute shaders, modern APIs, or high-resolution rendering, the Radeon 550 is the definitive choice.

Specification Differences

The two cards differ across nearly every measurable specification. The GT 640 uses a 28 nm process, while the Radeon 550 uses a 14 nm process. The GT 640 has 1,270 million transistors on a 118 mm² die, while the Radeon 550 has 2,200 million on a 103 mm² die. Transistor density is 10.8M/mm² for the GT 640 versus 21.4M/mm² for the Radeon 550. Memory type differs: DDR3 for the GT 640, GDDR5 for the Radeon 550. The GT 640's bus width is 128-bit; the Radeon 550's is 64-bit. Memory bandwidth is 28.51 GB/s versus 56.00 GB/s. Shading units: 384 versus 512. TMUs are equal at 32, and ROPs are equal at 16. Pixel rate is 7.216 GPixel/s versus 18.93 GPixel/s. Texture rate is 28.86 GTexel/s versus 37.86 GTexel/s. FP32 is 692.7 GFLOPS versus 1,211.4 GFLOPS. FP16 is not supported on the GT 640, but the Radeon 550 offers 1,211.4 GFLOPS. TDP is 65 W versus 50 W. Slot width is single-slot versus dual-slot. Bus interface is PCIe 3.0 x16 versus PCIe 3.0 x8. Display outputs: GT 640 has HDMI 1.4a and DisplayPort 1.2, while the Radeon 550 has HDMI 2.0b and DisplayPort 1.4a. DirectX support is 12 (11_0) versus 12 (12_0). Vulkan support is 1.2.175 versus 1.3. Release dates are 2012-06-04 for the GT 640 and 2017-04-19 for the Radeon 550. The launch MSRP for the GT 640 was 99 USD; the Radeon 550 launched at 79 USD.