AMD Radeon RX 6800 XT vs NVIDIA GeForce RTX 4090 Mobile Comparison

# AMD Radeon RX 6800 XT vs NVIDIA GeForce RTX 4090 Mobile

The benchmark data presents a fascinating contrast between a desktop flagship from 2020 and a mobile flagship from 2023. The NVIDIA GeForce RTX 4090 Mobile wins six of nine head-to-head tests, yet the AMD Radeon RX 6800 XT counters with significant victories in compute and 2D workloads, creating a nuanced picture that defies a simple "which is faster" verdict. The RTX 4090 Mobile's average benchmark score of 43,667 actually sits below the RX 6800 XT's 48,477, despite the NVIDIA part's superior performance in most individual graphics tests—a discrepancy that invites closer inspection of what each benchmark actually measures.

Head-to-Head Benchmarks

The most decisive NVIDIA victory comes in Geekbench Vulkan, where the RTX 4090 Mobile scores 170,774 against the RX 6800 XT's 136,875—a 19.9% gap that represents the largest delta in the entire comparison. This is not a marginal edge; it suggests fundamental advantages in how the Ada Lovelace architecture handles Vulkan's modern rendering paths. The Geekbench OpenCL result tells a different story, with NVIDIA leading 180,831 to 171,304, a much narrower 5.3% margin that hints at compute raw throughput being closer than rasterization performance.

The Passmark DirectX tests reveal a pattern of NVIDIA dominance in legacy and modern APIs alike. DirectX 9 shows the RTX 4090 Mobile ahead by 14.5% (310 vs 265), DirectX 10 by 10.4% (173 vs 155), and DirectX 12 by 6.5% (107 vs 100). Only in DirectX 11 does AMD claim victory, and barely—the RX 6800 XT's 264 edges out NVIDIA's 262 by a mere 0.8%, a statistical tie in practical terms. The Passmark G3D score, a composite gaming metric, favors NVIDIA by 8.2% (27,212 vs 24,980), reinforcing the pattern that the mobile GPU outpaces the desktop card in most gaming-oriented workloads.

AMD's wins are concentrated in specific compute and 2D scenarios. The Passmark GPU Compute test shows the RX 6800 XT leading by 7.3% (13,245 vs 12,347), a notable result given the NVIDIA part's higher FP32 throughput. The Passmark G2D score favors AMD by 4.7% (1,030 vs 984), indicating better raw 2D acceleration. With three wins for AMD and six for NVIDIA, the head-to-head tally favors NVIDIA, but the margins tell a more complex story: NVIDIA's wins range from 5.3% to 19.9%, while AMD's are 0.8%, 4.7%, and 7.3%. The RX 6800 XT punches hardest in compute, while the RTX 4090 Mobile's advantages are more broadly distributed across graphics APIs.

FAQ

Q: Which GPU wins more head-to-head benchmarks?

A: The NVIDIA GeForce RTX 4090 Mobile wins six of nine head-to-head tests, including Geekbench Vulkan, Geekbench OpenCL, Passmark DirectX 9, DirectX 10, DirectX 12, and Passmark G3D. The AMD Radeon RX 6800 XT wins the remaining three: Passmark DirectX 11, Passmark G2D, and Passmark GPU Compute.

Q: How large is the performance gap in Vulkan workloads?

A: The RTX 4090 Mobile leads by 19.9% in Geekbench Vulkan (170,774 vs 136,875), which is the largest performance delta between the two GPUs in any benchmark. This suggests a substantial architectural advantage for NVIDIA in Vulkan-based applications.

Q: Does the RX 6800 XT win any compute benchmarks?

A: Yes, the RX 6800 XT wins Passmark GPU Compute with a 7.3% margin (13,245 vs 12,347), despite the RTX 4090 Mobile having higher FP32 TFLOPS. The AMD card also wins Passmark G2D by 4.7% and Passmark DirectX 11 by 0.8%.

Q: What are the average benchmark scores for each GPU?

A: The RX 6800 XT has an average benchmark score of 48,477, while the RTX 4090 Mobile averages 43,667. Despite this, the RTX 4090 Mobile holds a higher percentile rank among all GPUs at 84%, compared to 85% for the RX 6800 XT.

Q: How do the nearest rivals compare for each GPU?

A: The RX 6800 XT's nearest rival is the NVIDIA RTX A1000 Mobile at 47,743 (1.5% lower), followed by the Intel Arc A550M at 49,737 (2.5% higher). The RTX 4090 Mobile's nearest rival is the NVIDIA Quadro M6000 at 43,301 (0.8% lower), with the RTX 5050 Mobile at 43,268 (0.9% lower).

Q: Which GPU has a higher Passmark G3D score?

A: The RTX 4090 Mobile achieves 27,212 in Passmark G3D, which is 8.2% higher than the RX 6800 XT's 24,980. This indicates NVIDIA's mobile flagship delivers better overall 3D graphics performance in this composite metric.

Architecture Differences

The architectural divide between these two GPUs is stark. The RX 6800 XT uses AMD's RDNA 2.0 architecture on a 7 nm TSMC process, packing 26,800 million transistors into a 520 mm² die with a transistor density of 51.5M per mm². The RTX 4090 Mobile employs NVIDIA's Ada Lovelace architecture on a more advanced 5 nm TSMC node, fitting 45,900 million transistors into a smaller 379 mm² die—yielding a dramatically higher transistor density of 121.1M per mm². This density advantage partially explains how NVIDIA achieves competitive or superior performance while consuming far less power.

The compute resources differ substantially. The RX 6800 XT features 4,608 shading units, 288 texture mapping units, 128 ROPs, and 72 ray tracing cores, with no tensor cores. The RTX 4090 Mobile counters with 9,728 shading units (more than double), 304 TMUs, 112 ROPs, 76 RT cores, and 304 tensor cores. The shading unit advantage is significant, yet the RX 6800 XT still wins the GPU compute benchmark—suggesting that raw unit counts don't tell the whole performance story.

Clock speeds reveal another layer of difference. The RX 6800 XT operates at a base clock of 1825 MHz with a boost of 2250 MHz and a game clock of 2015 MHz, while the RTX 4090 Mobile runs at a base of 1335 MHz and boost of 1695 MHz. The AMD card's higher clocks partially compensate for its fewer shading units. Memory clocks also differ: the RX 6800 XT runs GDDR6 at 2000 MHz (16 Gbps effective), while the RTX 4090 Mobile uses GDDR6 at 2250 MHz (18 Gbps effective), giving NVIDIA a bandwidth advantage of 576.0 GB/s versus 512.0 GB/s on the same 256-bit bus.

The FP32 compute figures highlight the theoretical gap: the RTX 4090 Mobile delivers 32.98 TFLOPS to the RX 6800 XT's 20.74 TFLOPS, a 59% advantage. However, FP16 tells a different story—the RX 6800 XT achieves 41.47 TFLOPS (2:1 ratio) while the RTX 4090 Mobile matches its FP32 at 32.98 TFLOPS (1:1 ratio). This means AMD has higher peak FP16 throughput despite lower FP32, which may explain its compute benchmark victory.

Specification Differences

The most obvious specification gap is power consumption. The RX 6800 XT carries a 300 W TDP and requires dual-slot cooling with 2x 8-pin power connectors and a 700 W suggested PSU. The RTX 4090 Mobile sips just 120 W, uses no power connectors, and is an IGP (integrated graphics package) with slot width listed as "IGP"—a fundamental difference in form factor and thermal envelope. The RX 6800 XT measures 267 mm in length, 120 mm in height, and 50 mm in width, while the RTX 4090 Mobile has no listed dimensions, reflecting its mobile nature.

Memory configurations are identical in capacity and bus width—both have 16 GB GDDR6 on a 256-bit bus—but bandwidth favors NVIDIA at 576.0 GB/s versus 512.0 GB/s. The RX 6800 XT offers specific display outputs (1x HDMI 2.1, 2x DisplayPort 1.4a, 1x USB Type-C), while the RTX 4090 Mobile's outputs are listed as "Portable Device Dependent," meaning they vary by laptop implementation. Production status differs: the RX 6800 XT is end-of-life, while the RTX 4090 Mobile is active. Release dates are December 2020 for AMD and January 2023 for NVIDIA.

Both GPUs support DirectX 12 Ultimate (12_2), OpenGL 4.6, and Vulkan 1.4, and both use PCIe 4.0 x16 interfaces. The RX 6800 XT has a launch MSRP of 649 USD, while the RTX 4090 Mobile has no listed MSRP. The RX 6800 XT's predecessor is Navi and successor is Navi III, while the RTX 4090 Mobile's predecessor is GeForce 30 Mobile and successor is GeForce 50 Mobile.

The Verdict

The data supports a split decision based on workload. For gaming and general 3D graphics, the RTX 4090 Mobile is the stronger performer, winning Passmark G3D by 8.2% and showing consistent advantages across DirectX 9, 10, and 12 APIs. The 19.9% Vulkan lead is particularly compelling for users running Vulkan-based games or applications. However, the RX 6800 XT's compute victory by 7.3% in Passmark GPU Compute, combined with its higher average benchmark score of 48,477 versus 43,667, indicates that AMD's desktop card remains competitive in compute-heavy tasks.

The power envelope is the decisive differentiator. The RTX 4090 Mobile achieves near-parity or superiority in most graphics tests while consuming 120 W versus 300 W—a 60% power reduction. This makes NVIDIA's mobile part remarkable for efficiency, but the RX 6800 XT's 300 W TDP enables higher clock speeds that partially offset its architectural disadvantages. The RX 6800 XT's percentile rank of 85% versus 84% for the RTX 4090 Mobile reflects its competitive standing despite fewer head-to-head wins.

Where Each One Wins

The RTX 4090 Mobile wins in Vulkan-heavy workloads, legacy DirectX titles (9, 10, 12), and composite 3D graphics performance. Its 19.9% Vulkan advantage suggests it is the better choice for Linux gaming, Vulkan-based game engines, and modern cross-platform titles. The DirectX wins indicate broad compatibility across gaming APIs, while the Passmark G3D lead confirms superior overall 3D acceleration. The 120 W TDP makes it suitable for laptops where power efficiency is paramount.

The RX 6800 XT wins in compute-intensive tasks, as shown by its 7.3% Passmark GPU Compute lead, making it stronger for GPGPU workloads, scientific computing, and compute-shader-heavy applications. Its 4.7% G2D advantage indicates better 2D desktop performance. The DirectX 11 win, though marginal at 0.8%, covers a still-common API in older titles and productivity software. The higher average benchmark score of 48,477 versus 43,667 suggests that across a wider benchmark suite, the RX 6800 XT holds its own despite losing most head-to-head comparisons. For desktop users with power to spare, the RX 6800 XT remains a viable compute and 2D performer; for mobile users prioritizing graphics and efficiency, the RTX 4090 Mobile is the clear choice.