AMD Radeon RX 6900 XT vs NVIDIA GeForce RTX 4090 Mobile Comparison

Head-to-Head Benchmarks

The benchmark data splits nearly evenly between these two GPUs, with the AMD Radeon RX 6900 XT taking five wins and the NVIDIA GeForce RTX 4090 Mobile taking four. The largest margin of victory belongs to the AMD card in Passmark GPU Compute, where it scores 14,547 against the NVIDIA's 12,347 — a decisive 17.8% advantage. This is the single biggest delta in the entire head-to-head set, and it signals that the RX 6900 XT has a clear edge in compute-oriented workloads despite being an end-of-life desktop part.

The NVIDIA GeForce RTX 4090 Mobile counters with its own commanding win in Passmark DirectX 9, posting 310 versus 268 for the AMD card, a 13.5% gap. It also takes Geekbench Vulkan by a wide margin, 170,774 to 148,525, which is a 13% difference. Those two results show the mobile NVIDIA part pulling ahead in legacy DirectX and modern Vulkan API performance, respectively.

The remaining matchups are much tighter. In Passmark G3D, the NVIDIA card edges out a 27,212 to 26,732 win, a slim 1.8% margin. The AMD card wins Passmark DirectX 11 by 6.5% (279 to 262) and Passmark DirectX 12 by 5.6% (113 to 107). Geekbench OpenCL goes to AMD by 3.8%, with scores of 187,673 against 180,831. Passmark DirectX 10 is nearly a tie, with NVIDIA ahead by just 3.5% (173 to 167), while Passmark G2D favors AMD by 7.2% (1,055 to 984).

The average benchmark scores tell a more complex story. The RX 6900 XT has an average score of 50,951, placing it in the 86th percentile of all GPUs. Its nearest rivals include the NVIDIA CMP 50HX (1.6% ahead), the AMD Radeon RX Vega 64 (1.9% behind), the NVIDIA GeForce RTX 5070 Ti (2% behind), and the Intel Arc A550M (2.4% behind). The RTX 4090 Mobile, by contrast, has an average score of 43,667, putting it in the 84th percentile. Its nearest rivals are the NVIDIA RTX A6000 (0.9% ahead), the Quadro M6000 (0.8% behind), the RTX 5050 Mobile (0.9% behind), and the Quadro M6000 24 GB (0.9% behind). The desktop AMD card holds a 16.7% advantage in average score over the mobile NVIDIA part.

Architecture Differences

The two GPUs are built on fundamentally different architectures and process nodes. The AMD Radeon RX 6900 XT uses the Navi 21 chip with RDNA 2.0 architecture, fabricated on TSMC's 7 nm process. It packs 26,800 million transistors into a 520 mm² die, yielding a transistor density of 51.5 million per square millimeter. The NVIDIA GeForce RTX 4090 Mobile uses the AD103 chip with Ada Lovelace architecture, built on TSMC's 5 nm process. It contains 45,900 million transistors on a smaller 379 mm² die, achieving a much higher density of 121.1 million per square millimeter.

The compute resources differ substantially. The AMD card has 5,120 shading units, 320 texture mapping units, and 128 raster output pipelines. The NVIDIA card has nearly double the shading units at 9,728, but slightly fewer TMUs at 304 and fewer ROPs at 112. For ray tracing, the RX 6900 XT has 80 RT cores while the RTX 4090 Mobile has 76 — a marginal difference. The NVIDIA card also includes 304 tensor cores, a feature entirely absent from the AMD part.

Clock speeds and raw throughput tell a nuanced story. The AMD card runs at a 1,825 MHz base and 2,250 MHz boost clock, with a game clock of 2,015 MHz. The NVIDIA card has a lower 1,335 MHz base and 1,695 MHz boost. Despite lower clocks, the NVIDIA card achieves higher FP32 throughput at 32.98 TFLOPS compared to 23.04 TFLOPS for AMD. The FP16 numbers are telling: AMD delivers 46.08 TFLOPS at a 2:1 ratio, while NVIDIA matches its FP32 at 32.98 TFLOPS with a 1:1 ratio. Pixel rates favor AMD at 288.0 GPixel/s versus 189.8 GPixel/s, and texture rates also favor AMD at 720.0 GTexel/s against 515.3 GTexel/s.

Memory configurations are similar in capacity but differ in speed. Both have 16 GB of GDDR6 on a 256-bit bus. The AMD card runs memory at 2,000 MHz with 16 Gbps effective speed, yielding 512.0 GB/s bandwidth. The NVIDIA card runs memory at 2,250 MHz with 18 Gbps effective speed, achieving 576.0 GB/s. Power consumption is a stark contrast: the RX 6900 XT has a 300 W TDP with dual 8-pin power connectors and a 700 W suggested PSU, while the RTX 4090 Mobile is rated at just 120 W with no power connectors, being an integrated graphics package.

Where Each One Wins

The AMD Radeon RX 6900 XT dominates in compute-heavy workloads. Its 17.8% lead in Passmark GPU Compute is the standout result, and it also wins Geekbench OpenCL with 187,673 points. The AMD card takes Passmark DirectX 11 and DirectX 12 benchmarks, suggesting strong compatibility with current-generation DirectX titles. Its 7.2% win in Passmark G2D indicates superior 2D graphics performance, which can matter for desktop productivity and non-gaming applications.

The NVIDIA GeForce RTX 4090 Mobile excels in different areas. Its 13.5% win in Passmark DirectX 9 shows strong legacy API performance, while the 13% advantage in Geekbench Vulkan points to modern API efficiency. The NVIDIA card also wins Passmark G3D by 1.8%, which is a general 3D graphics score that aggregates multiple DirectX tests. Its Passmark DirectX 10 win, while narrow at 3.5%, adds to the pattern of NVIDIA strength across the Passmark 3D suite.

The overall percentile rankings put the AMD card slightly higher at 86th percentile versus 84th for NVIDIA. The average score difference of 7,284 points (50,951 versus 43,667) represents a 16.7% gap in favor of the desktop AMD part. However, the RTX 4090 Mobile achieves this performance at a fraction of the power draw — 120 W versus 300 W — which is a critical distinction for mobile use cases.

The Verdict

The data presents a clear choice based on use case and platform. The AMD Radeon RX 6900 XT is the stronger overall performer, with a higher average benchmark score, a better percentile ranking, and wins in five of the nine head-to-head tests. Its compute lead is substantial, and it holds advantages in DirectX 11, DirectX 12, OpenCL, and 2D workloads. This card is a triple-slot desktop part requiring a 700 W power supply, so it belongs in a full desktop build where raw performance is the priority.

The NVIDIA GeForce RTX 4090 Mobile is the more efficient package. It delivers 84th percentile performance at 120 W, which is less than half the power of the AMD card. Its wins in Vulkan, DirectX 9, and DirectX 10 show strength in API-specific scenarios. The inclusion of tensor cores makes it a more feature-complete part for accelerated AI workloads, though the benchmark data does not directly measure that capability. As an active production part from the GeForce 40-series, it also has a newer release date of January 2023 versus October 2020 for the AMD card.

For a desktop system with a robust power supply and space for a triple-slot card, the RX 6900 XT is the better choice based on raw scores. For a laptop or compact system where the 120 W power envelope and integrated form factor are requirements, the RTX 4090 Mobile is the only viable option in this comparison. The 16.7% average score gap is significant, but the NVIDIA card's efficiency and feature set may compensate in mobile environments.

FAQ

Q: Which GPU has the higher average benchmark score?

A: The AMD Radeon RX 6900 XT has an average benchmark score of 50,951, compared to 43,667 for the NVIDIA GeForce RTX 4090 Mobile. This represents a 16.7% advantage for the AMD card.

Q: How do the two GPUs compare in ray tracing hardware?

A: The AMD Radeon RX 6900 XT has 80 ray tracing cores, while the NVIDIA GeForce RTX 4090 Mobile has 76. The NVIDIA card additionally includes 304 tensor cores, which the AMD card does not have.

Q: What is the power consumption difference?

A: The AMD Radeon RX 6900 XT has a 300 W TDP and requires a 700 W suggested power supply with dual 8-pin connectors. The NVIDIA GeForce RTX 4090 Mobile has a 120 W TDP and uses no power connectors, being an integrated graphics package.

Q: Which GPU wins in Vulkan performance?

A: The NVIDIA GeForce RTX 4090 Mobile wins Geekbench Vulkan with a score of 170,774, compared to 148,525 for the AMD Radeon RX 6900 XT. This is a 13% advantage for the NVIDIA card.

Q: What are the memory bandwidth specifications for each?

A: Both GPUs have 16 GB of GDDR6 memory on a 256-bit bus. The AMD Radeon RX 6900 XT achieves 512.0 GB/s bandwidth, while the NVIDIA GeForce RTX 4090 Mobile achieves 576.0 GB/s.

Q: How do the GPUs compare in transistor count and die size?

A: The AMD Radeon RX 6900 XT contains 26,800 million transistors on a 520 mm² die. The NVIDIA GeForce RTX 4090 Mobile contains 45,900 million transistors on a smaller 379 mm² die, giving it a higher transistor density of 121.1M per mm² versus 51.5M per mm² for AMD.