AMD Radeon RX 550X vs NVIDIA GeForce GTX 660 Comparison

Where Each One Wins

The benchmark data presents a clear split between these two end-of-life graphics cards. The NVIDIA GeForce GTX 660 wins both recorded head-to-head benchmark comparisons, taking the OpenCL and Vulkan tests. The AMD Radeon RX 550X does not record a single win in the direct comparison, though its average benchmark score across all recorded tests is higher than the GTX 660's average.

The AMD Radeon RX 550X achieves an average benchmark score of 10,481, placing it in the 49th percentile of all GPUs in the database. The NVIDIA GeForce GTX 660, by contrast, has an average benchmark score of 9,022, placing it in the 45th percentile. This means the RX 550X sits slightly higher in the overall performance distribution, even though it loses the specific head-to-head tests.

In terms of nearest rivals, the RX 550X sits close to the NVIDIA Tesla C2075 (0.8% ahead), the AMD Radeon RX 6500M (1.2% ahead), while trailing the AMD Radeon R9 M275X by 1% and the AMD Radeon RX 6600S by 1.4%. The GTX 660's nearest rivals include the NVIDIA TITAN V CEO Edition (0.2% ahead), the NVIDIA GeForce GTX 560 (0.4% ahead), and the AMD Radeon 550X (1.2% behind), with the AMD Radeon Pro WX 5100 trailing by 1.8%.

The use-case split favors the GTX 660 for compute workloads where OpenCL performance matters, and for Vulkan-based applications. The RX 550X's advantage lies in its higher overall benchmark average, suggesting more consistent performance across a broader range of tests, even if it loses the two specific comparisons recorded.

Architecture Differences

The AMD Radeon RX 550X uses the Lexa chip built on the GCN 4.0 architecture, fabricated on a 14 nm process at GlobalFoundries. It belongs to the Polaris (RX 500X) generation. The NVIDIA GeForce GTX 660 uses the GK106 chip on the Kepler architecture, fabricated on a 28 nm process at TSMC, and belongs to the GeForce 600 generation.

The transistor counts differ significantly. The RX 550X packs 2,200 million transistors on a 103 mm² die, yielding a transistor density of 21.4 million per mm². The GTX 660 contains 2,540 million transistors on a much larger 221 mm² die, resulting in a lower density of 11.5 million per mm². The newer manufacturing process gives AMD a clear density advantage.

Compute resources also differ. The RX 550X has 512 shading units, 32 texture mapping units, and 16 render output units. The GTX 660 has nearly double the shading units at 960, along with 80 TMUs and 24 ROPs. Despite having fewer shaders, the RX 550X posts a pixel rate of 18.93 GPixel/s versus 20.64 GPixel/s for the GTX 660, and a texture rate of 37.86 GTexel/s versus 82.56 GTexel/s for the GTX 660.

The RX 550X supports DirectX 12 (12_0), OpenGL 4.6, and Vulkan 1.3. The GTX 660 supports DirectX 12 (11_0), OpenGL 4.6, and Vulkan 1.2.175. The newer AMD architecture carries a higher Vulkan version and a more complete DirectX 12 feature level.

Memory configurations vary. The RX 550X uses 4 GB of GDDR5 on a 128-bit bus, delivering 96.00 GB/s of bandwidth. The GTX 660 uses 2 GB of GDDR5 on a 192-bit bus, delivering 144.2 GB/s. The GTX 660 has the bandwidth advantage, while the RX 550X has double the capacity.

Power characteristics differ substantially. The RX 550X has a 50 W TDP and requires no power connectors, with a suggested PSU of 250 W. The GTX 660 has a 140 W TDP, requires one 6-pin connector, and suggests a 300 W PSU. The RX 550X is far more power-efficient per the specifications.

The RX 550X uses a PCIe 3.0 x8 interface, while the GTX 660 uses PCIe 3.0 x16. Display outputs also differ: the RX 550X offers one DVI, one HDMI 2.0b, and one DisplayPort 1.4a. The GTX 660 offers two DVI, one HDMI 1.4a, and one DisplayPort 1.2.

Head-to-Head Benchmarks

The recorded head-to-head results show the NVIDIA GeForce GTX 660 winning both tests. In Geekbench OpenCL, the GTX 660 scores 11,347 against 9,662 for the RX 550X, a delta of negative 14.8% from the RX 550X's perspective. That is a decisive margin, placing the GTX 660 roughly 17% ahead of the RX 550X in that workload.

The Vulkan test is much closer. The GTX 660 scores 11,415 against 11,299 for the RX 550X, a delta of only negative 1%. This near-tie suggests the RX 550X's newer architecture nearly closes the gap in Vulkan, despite the GTX 660's higher raw compute resources.

Looking at the individual benchmark records, the RX 550X's OpenCL score of 9,662 is significantly lower than its Vulkan score of 11,299. The GTX 660 shows less variance: 11,347 in OpenCL and 11,415 in Vulkan. The GTX 660's OpenCL performance is its strongest recorded result, while the RX 550X's Vulkan performance is its strongest.

The average benchmark scores tell a different story. The RX 550X averages 10,481 across its recorded tests, while the GTX 660 averages 9,022. This discrepancy arises because the GTX 660 also has a Geekbench Metal score of 4,305, which drags its average down considerably. The RX 550X has no Metal score recorded.

In the nearest rival comparisons, the RX 550X's 10,481 average sits 0.8% above the NVIDIA Tesla C2075's 10,400, and 1.2% above the AMD Radeon RX 6500M's 10,362. It trails the AMD Radeon R9 M275X by 1% and the AMD Radeon RX 6600S by 1.4%. The GTX 660's 9,022 average sits 0.2% below the NVIDIA TITAN V CEO Edition's 9,037 and 0.4% below the NVIDIA GeForce GTX 560's 9,058, while sitting 1.2% above the AMD Radeon 550X's 8,918 and 1.8% above the AMD Radeon Pro WX 5100's 8,863.

FAQ

Q: Which card wins the most head-to-head benchmark comparisons?

A: The NVIDIA GeForce GTX 660 wins both recorded head-to-head tests, taking Geekbench OpenCL and Geekbench Vulkan. The AMD Radeon RX 550X records zero wins in the direct comparison.

Q: How large is the performance gap in OpenCL?

A: The GTX 660 scores 11,347 in Geekbench OpenCL versus 9,662 for the RX 550X, a delta of negative 14.8% from the RX 550X's position. This is the largest margin between the two cards in any recorded test.

Q: Is the RX 550X competitive in Vulkan?

A: Yes. The RX 550X scores 11,299 in Geekbench Vulkan against 11,415 for the GTX 660, a delta of only negative 1%. This is a near-tie and represents the RX 550X's strongest recorded result.

Q: Why does the RX 550X have a higher average benchmark score if it loses the head-to-head tests?

A: The RX 550X averages 10,481 across its two recorded tests. The GTX 660 averages 9,022 across three tests, including a Geekbench Metal score of 4,305, which significantly lowers its average. The RX 550X has no Metal test recorded.

Q: How do the cards compare in terms of overall percentile ranking?

A: The RX 550X sits in the 49th percentile of all GPUs in the database, while the GTX 660 sits in the 45th percentile. The RX 550X ranks slightly higher despite losing the direct comparisons.

Q: What are the closest rivals for each card?

A: For the RX 550X, the closest rival is the NVIDIA Tesla C2075, with the RX 550X ahead by 0.8%. For the GTX 660, the closest rival is the NVIDIA TITAN V CEO Edition, with the GTX 660 behind by 0.2%.

Specification Differences

| Specification | AMD Radeon RX 550X | NVIDIA GeForce GTX 660 |

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

| Architecture | GCN 4.0 | Kepler |

| Process node | 14 nm | 28 nm |

| Foundry | GlobalFoundries | TSMC |

| Transistors | 2,200 million | 2,540 million |

| Die size | 103 mm² | 221 mm² |

| Transistor density | 21.4M / mm² | 11.5M / mm² |

| Base clock | 1100 MHz | 980 MHz |

| Boost clock | 1183 MHz | 1032 MHz |

| Memory size | 4 GB | 2 GB |

| Memory bus width | 128 bit | 192 bit |

| Memory bandwidth | 96.00 GB/s | 144.2 GB/s |

| Shading units | 512 | 960 |

| TMUs | 32 | 80 |

| ROPs | 16 | 24 |

| Pixel rate | 18.93 GPixel/s | 20.64 GPixel/s |

| Texture rate | 37.86 GTexel/s | 82.56 GTexel/s |

| FP32 performance | 1,211.4 GFLOPS | 1.981 TFLOPS |

| FP16 performance | 1,211.4 GFLOPS (1:1) | null |

| TDP | 50 W | 140 W |

| Power connectors | None | 1x 6-pin |

| Suggested PSU | 250 W | 300 W |

| Bus interface | PCIe 3.0 x8 | PCIe 3.0 x16 |

| Display outputs | 1x DVI, 1x HDMI 2.0b, 1x DisplayPort 1.4a | 2x DVI, 1x HDMI 1.4a, 1x DisplayPort 1.2 |

| DirectX support | 12 (12_0) | 12 (11_0) |

| Vulkan support | 1.3 | 1.2.175 |

| OpenGL support | 4.6 | 4.6 |

| Length | 145 mm (5.7 inches) | 241 mm (9.5 inches) |

| Release date | 2018-12-15 | 2012-09-05 |

| Launch MSRP | null | 229 USD |

The RX 550X is a smaller, more efficient card with a shorter length of 145 mm versus 241 mm for the GTX 660. Both are dual-slot designs. The RX 550X draws 50 W with no power connector, while the GTX 660 draws 140 W and requires a 6-pin connector. The RX 550X also has a faster base and boost clock, but the GTX 660 has substantially more shading units, TMUs, ROPs, and memory bandwidth.

The GTX 660 was released on 2012-09-05 with a launch MSRP of 229 USD. The RX 550X was released on 2018-12-15 with no launch MSRP recorded. Both are end-of-life products. The RX 550X's predecessor is Polaris and successor is Vega. The GTX 660's predecessor is GeForce 500 and successor is GeForce 700.