AMD Radeon RX 6600 XT vs NVIDIA GeForce RTX 3090 Comparison

Where Each One Wins

The recorded benchmark data splits these two cards along clear workload lines. NVIDIA GeForce RTX 3090 wins 9 of the 10 head-to-head tests, while AMD Radeon RX 6600 XT takes a single, but notable, victory. The RTX 3090 dominates in raw compute, DirectX 9, 10, 11, and 12 workloads, 3DMark Steel Nomad, OpenCL, and general 3D rendering. The RX 6600 XT wins only in Vulkan, where it posts a 72,417 score against the RTX 3090's 53,927, a 25.5% advantage. That single win indicates the AMD card has a specific strength in Vulkan-based applications, likely due to driver scheduling or API overhead characteristics. For every other measured category, the RTX 3090 leads, often by substantial margins. The use-case split is therefore straightforward: the RTX 3090 is the general-purpose heavy lifter, while the RX 6600 XT should be considered only if your workload is exclusively Vulkan and you are willing to sacrifice massive performance elsewhere.

Architecture Differences

The two GPUs come from fundamentally different design philosophies. NVIDIA's GA102 chip, built on Samsung's 8 nm process, packs 28,300 million transistors into a 628 mm² die, yielding a transistor density of 45.1 million per mm². AMD's Navi 23, fabricated by TSMC on 7 nm, contains 11,060 million transistors on a 237 mm² die, with a density of 46.7 million per mm². The RTX 3090 uses Ampere architecture with 10,496 shading units, 328 texture mapping units, and 112 render output units. It also carries 82 RT cores and 328 tensor cores, the latter enabling dedicated AI acceleration that the RX 6600 XT lacks entirely. AMD's RDNA 2.0 design fields 2,048 shading units, 128 TMUs, and 64 ROPs, with 32 RT cores and no tensor cores. Memory subsystems diverge sharply: the RTX 3090 has 24 GB of GDDR6X on a 384-bit bus, delivering 936.2 GB/s, while the RX 6600 XT has 8 GB of GDDR6 on a 128-bit bus, providing 256.0 GB/s. Clock behavior differs too. The RX 6600 XT runs a base clock of 1968 MHz and boosts to 2589 MHz, with a game clock of 2359 MHz. The RTX 3090's base is 1395 MHz, boosting to 1695 MHz. Despite lower clocks, the RTX 3090 achieves far higher throughput due to its massive shader count. Pixel rates tell the story: 189.8 GPixel/s for NVIDIA versus 165.7 GPixel/s for AMD. Texture rates are 556.0 GTexel/s versus 331.4 GTexel/s. FP32 compute is 35.58 TFLOPS for the RTX 3090, more than triple the RX 6600 XT's 10.60 TFLOPS. The AMD card's FP16 rating is 21.21 TFLOPS at a 2:1 ratio, while the RTX 3090 offers 35.58 TFLOPS FP16 at a 1:1 ratio, meaning it does not halve throughput for half precision. Power envelopes reflect these differences: 350 W TDP for NVIDIA versus 160 W for AMD. Physical dimensions also contrast sharply, with the RTX 3090 being 336 mm long, 140 mm tall, and 61 mm wide, versus the RX 6600 XT's 190 mm length, 110 mm height, and 40 mm width. Both use PCIe 4.0, but the RTX 3090 runs x16 while the RX 6600 XT uses x8. Both support DirectX 12 Ultimate, OpenGL 4.6, and Vulkan 1.4, and both have identical display outputs: 1x HDMI 2.1 and 3x DisplayPort 1.4a.

Head-to-Head Benchmarks

The largest single delta in the entire dataset comes from 3DMark Steel Nomad DX12, where the RTX 3090 scores 5,118 against the RX 6600 XT's 1,804, a 183.7% advantage. That is not a marginal lead; it is a near-tripling of performance in a modern DirectX 12 workload. Geekbench OpenCL shows a 114.6% difference, with the RTX 3090 at 172,758 and the RX 6600 XT at 80,503. Passmark GPU Compute gives the RTX 3090 a 104.2% lead, 15,356 versus 7,520. These three tests illustrate the compute-heavy nature of the RTX 3090's advantage. In DirectX 12, the RTX 3090 scores 110 against 61, an 80.3% delta. DirectX 10 shows a 67% lead, 182 versus 109. DirectX 11 is closer, with the RTX 3090 at 220 and the RX 6600 XT at 163, a 35% edge. DirectX 9 has a 38.1% delta, 268 versus 194. Passmark G3D, a general 3D rendering test, gives the RTX 3090 a 61.9% lead, 26,645 versus 16,461. Even 2D performance favors the RTX 3090, with a 16.6% delta in Passmark G2D, 1,063 versus 912. The only reverse result is Geekbench Vulkan, where the RX 6600 XT leads by 25.5%, 72,417 versus 53,927. That Vulkan result is particularly striking because the RX 6600 XT loses by over 100% in OpenCL and compute tests, yet wins decisively in Vulkan. This suggests the AMD architecture has a specific Vulkan optimization or driver advantage that does not translate to other APIs. Across all ten tests, the average benchmark score for the RTX 3090 is 27,565, while the RX 6600 XT averages 24,442. The RTX 3090 sits at the 73rd percentile among all GPUs, the RX 6600 XT at the 70th.

FAQ

Q: Which card wins in DirectX 12 performance?

A: The RTX 3090 wins decisively. In Passmark DirectX 12, it scores 110 against the RX 6600 XT's 61, an 80.3% advantage. In 3DMark Steel Nomad DX12, the RTX 3090 leads by 183.7%, scoring 5,118 versus 1,804.

Q: Does the AMD card win any benchmark at all?

A: Yes, in Geekbench Vulkan. The RX 6600 XT scores 72,417, which is 25.5% higher than the RTX 3090's 53,927. This is the only test among the ten head-to-head comparisons where AMD leads.

Q: How large is the compute performance gap?

A: Very large. In Passmark GPU Compute, the RTX 3090 scores 15,356 versus 7,520, a 104.2% lead. Geekbench OpenCL shows a 114.6% delta, with the RTX 3090 at 172,758 and the RX 6600 XT at 80,503.

Q: What are the memory configuration differences?

A: The RTX 3090 has 24 GB of GDDR6X on a 384-bit bus, yielding 936.2 GB/s bandwidth. The RX 6600 XT has 8 GB of GDDR6 on a 128-bit bus, providing 256.0 GB/s. This is a 3.66x bandwidth advantage for NVIDIA.

Q: Which card has higher clock speeds?

A: The RX 6600 XT. Its base clock is 1968 MHz and boost is 2589 MHz, with a game clock of 2359 MHz. The RTX 3090's base is 1395 MHz and boost is 1695 MHz. Despite lower clocks, the RTX 3090 achieves higher throughput due to more shaders and memory bandwidth.

Q: How do the cards compare in older DirectX versions?

A: The RTX 3090 leads in all legacy DirectX tests. DirectX 9 shows a 38.1% delta (268 versus 194), DirectX 10 shows a 67% delta (182 versus 109), and DirectX 11 shows a 35% delta (220 versus 163).

Specification Differences

| Specification | NVIDIA GeForce RTX 3090 | AMD Radeon RX 6600 XT |

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

| Chip | GA102 | Navi 23 |

| Architecture | Ampere | RDNA 2.0 |

| Process Node | 8 nm (Samsung) | 7 nm (TSMC) |

| Transistors | 28,300 million | 11,060 million |

| Die Size | 628 mm² | 237 mm² |

| Transistor Density | 45.1M / mm² | 46.7M / mm² |

| Base Clock | 1395 MHz | 1968 MHz |

| Boost Clock | 1695 MHz | 2589 MHz |

| Game Clock | N/A | 2359 MHz |

| Memory Speed | 19.5 Gbps effective | 16 Gbps effective |

| Memory Size | 24 GB | 8 GB |

| Memory Type | GDDR6X | GDDR6 |

| Memory Bus Width | 384 bit | 128 bit |

| Memory Bandwidth | 936.2 GB/s | 256.0 GB/s |

| Shading Units | 10496 | 2048 |

| TMUs | 328 | 128 |

| ROPs | 112 | 64 |

| RT Cores | 82 | 32 |

| Tensor Cores | 328 | None |

| Pixel Rate | 189.8 GPixel/s | 165.7 GPixel/s |

| Texture Rate | 556.0 GTexel/s | 331.4 GTexel/s |

| FP32 Performance | 35.58 TFLOPS | 10.60 TFLOPS |

| FP16 Performance | 35.58 TFLOPS (1:1) | 21.21 TFLOPS (2:1) |

| TDP | 350 W | 160 W |

| Slot Width | Triple-slot | Dual-slot |

| Power Connectors | 1x 12-pin | 1x 8-pin |

| Suggested PSU | 750 W | 450 W |

| Bus Interface | PCIe 4.0 x16 | PCIe 4.0 x8 |

| Length | 336 mm | 190 mm |

| Height | 140 mm | 110 mm |

| Width | 61 mm | 40 mm |

| Release Date | 2020-08-31 | 2021-07-29 |

| Launch MSRP | 1,499 USD | 379 USD |

The Verdict

The recorded data leads to an unambiguous conclusion for most users. If your priority is maximum performance across DirectX 9 through 12, OpenCL, compute workloads, and general 3D rendering, the RTX 3090 is the clear choice. It wins 9 of 10 benchmarks, with deltas ranging from 16.6% in 2D performance to 183.7% in 3DMark Steel Nomad. The only scenario where the RX 6600 XT is preferable is Vulkan-specific applications, where it holds a 25.5% advantage. However, that single win comes with massive compromises elsewhere. The RTX 3090 offers 24 GB of GDDR6X memory versus 8 GB of GDDR6, a 384-bit bus versus 128-bit, and 936.2 GB/s bandwidth versus 256.0 GB/s. It has 5.1x the shading units, 2.6x the TMUs, 1.75x the ROPs, and 2.6x the RT cores. Its FP32 compute is 3.36x higher. The RX 6600 XT does have advantages in power efficiency, with a 160 W TDP versus 350 W, and a smaller physical footprint at 190 mm versus 336 mm. It also has a higher boost clock at 2589 MHz versus 1695 MHz. For users building a compact system with modest power delivery, the RX 6600 XT is viable, but only if Vulkan performance is the primary metric. The RTX 3090's average benchmark score of 27,565 places it at the 73rd percentile of all GPUs, while the RX 6600 XT's 24,442 average sits at the 70th. The RTX 3090's nearest rivals are the RTX 4070 Mobile and RX 6700 XT, both within 0.5%, while the RX 6600 XT sits near the GTX 1630 and RTX 2080 SUPER. The data shows a clear hierarchy: the RTX 3090 is a high-end flagship, the RX 6600 XT a mid-range part. Choose the RTX 3090 for raw performance, the RX 6600 XT only for Vulkan-specific workloads or where size and power constraints are absolute.