Rust

The Intel Core i5-10400F paired with the NVIDIA GeForce RTX 5090 presents a striking imbalance in Rust, a title where the 2018-era CPU architecture struggles to feed one of the fastest consumer GPUs available. The data reveals a system consistently bound by processor throughput rather than graphics horsepower, yet the RTX 5090 still manages to deliver playable frame rates across most configurations. This analysis breaks down the measured results, focusing on where the bottleneck manifests and what the numbers indicate about component roles.

Resolution Scaling

The frame rate scaling from 1080p to 4K in Rust follows a pattern that clearly identifies the CPU as the primary constraint. At 1920x1080 with Low settings, the combo achieves 146.3 FPS, while at 2560x1440 Low the average drops to 133.6 FPS, and at 3840x2160 Low it falls further to 109.7 FPS. The delta from 1080p to 1440p is 12.7 FPS, and from 1440p to 4K it is 23.9 FPS. This relatively modest drop across a 4x increase in pixel count suggests that the processor is already limiting performance even at the lowest resolution, preventing the GPU from fully stretching its legs.

Moving to High settings, the scaling becomes even more compressed. The 1080p High average is 123.9 FPS, dropping to 108.8 FPS at 1440p and 77.2 FPS at 4K. The 46.7 FPS gap between 1080p and 4K High is larger than the Low preset gap, indicating that the graphics card begins to take on more responsibility as settings increase. However, the fact that 4K High still holds above 60 FPS suggests the RTX 5090 has ample headroom, and the real bottleneck remains the six-core Comet Lake processor. The Ultra preset tells a similar story: 107.9 FPS at 1080p, 96.3 FPS at 1440p, and 58.2 FPS at 4K, with the 4K result finally dipping below the 60 FPS threshold.

The data indicates that resolution scaling in Rust is partially mitigated by the CPU limit. If the GPU were the sole constraint, the 4K frame rates would be dramatically lower relative to 1080p, given the massive pixel count increase. Instead, the observed deltas are moderate, which points to a situation where the i5-10400F saturates its threads around the 110-145 FPS range at lower resolutions, and only at 4K Ultra does the RTX 5090’s workload become heavy enough to push the system into a more GPU-bound state.

CPU Role

The Intel Core i5-10400F is a 6-core, 12-thread processor from the Comet Lake generation, built on a 14 nm process. Its base clock is 2.90 GHz with a boost clock of 4.30 GHz, and it carries 12 MB of shared L3 cache. In synthetic benchmarks, the CPU scores 10,297 in Cinebench R23 multi-core and 1,453 in single-core, placing it in the 73rd percentile against all CPUs. Its nearest rivals include the AMD EPYC 7552 (0.4% ahead in average score) and the Intel Core i5-8500 (1.1% behind), showing that this chip sits in a crowded mid-range tier.

In Rust, which is known for heavy single-threaded server-side simulation and physics calculations, the i5-10400F’s single-core prowess is tested heavily. The 3DMark single-thread score of 688 and passmark single-thread score of 2,541 suggest modest per-core performance compared to modern chips. The boost clock of 4.30 GHz helps, but the architecture lacks the IPC improvements of newer generations. The measured frame rates at 1080p Low (146.3 FPS) likely represent near the ceiling for this CPU in Rust, as the game’s simulation logic becomes the limiting factor before the GPU is fully utilized.

The 12 threads provide some headroom for background tasks and the game’s multithreaded rendering pipeline, but the Cinebench R15 multi-core score of 1,037 indicates that scaling beyond six cores is limited. The 3DMark 16-thread score of 4,748 versus the max-thread score of 4,735 shows that the processor does not gain significant performance beyond its physical core count, which aligns with Rust’s reliance on fewer, faster threads. The CPU’s memory bandwidth of 42.7 GB/s with dual-channel DDR4 support is adequate for the game’s needs but not exceptional, potentially contributing to minor stutters in busy scenes.

GPU Role

The NVIDIA GeForce RTX 5090 is a flagship Blackwell 2.0 architecture GPU with 21,760 shading units, 170 RT cores, and 680 tensor cores. It features 32 GB of GDDR7 memory on a 512-bit bus, delivering 1.79 TB/s of bandwidth. The boost clock is rated at 2407 MHz, and the GPU achieves a Passmark G3D score of 39,650, placing it in the 94th percentile against all GPUs. Its nearest rivals include the RTX 5090 D (0.1% ahead) and the RTX 5050 Mobile (0.2% ahead), though those comparisons are based on average benchmark scores rather than gaming performance.

In Rust, the RTX 5090’s role is somewhat diminished by the CPU bottleneck, but the GPU still dictates the maximum quality settings achievable. The 32 GB VRAM is far beyond what Rust requires, even at 4K Ultra with high-resolution texture packs. The memory bandwidth of 1.79 TB/s ensures that texture streaming and draw calls are never constrained by VRAM capacity or speed. The pixel rate of 423.6 GPixel/s and texture rate of 1,636.8 GTexel/s are more than sufficient to handle the game’s relatively simple geometry and lighting.

The GPU’s FP32 throughput of 104.8 TFLOPS is excessive for Rust’s DX12 rendering path, which is why the measured FPS differences between Low and Ultra at a given resolution are not as large as one might expect. For example, at 1440p, the spread between Low (133.6 FPS) and Ultra (96.3 FPS) is 37.3 FPS, indicating the GPU does have some impact as settings increase. At 1080p, the spread narrows to 38.4 FPS (146.3 Low vs. 107.9 Ultra), which suggests the CPU is capping the upper bound more tightly at lower resolutions. The RTX 5090’s role becomes more pronounced at 4K, where the Ultra preset drops to 58.2 FPS, showing that even this GPU can be challenged by the game’s most demanding settings at maximum resolution.

Measured FPS Breakdown

At 1920x1080, the combo delivers 146.3 FPS on Low, 129.0 FPS on Medium, 123.9 FPS on High, and 107.9 FPS on Ultra. The jump from Low to Ultra costs 38.4 FPS, a 26.3% reduction, which is modest given the visual quality increase. The 1080p results are consistently above 100 FPS, making this resolution entirely playable for competitive scenarios, though the CPU limit prevents the RTX 5090 from reaching its full potential.

At 2560x1440, the averages are 133.6 FPS on Low, 111.4 FPS on Medium, 108.8 FPS on High, and 96.3 FPS on Ultra. The 1440p results remain strong, with even Ultra staying above 90 FPS. The delta between Low and Ultra here is 37.3 FPS, nearly identical to 1080p, reinforcing that the CPU is the primary limiter across these two resolutions. The GPU’s added workload at 1440p is absorbed without significant frame rate penalties, as the RTX 5090 has ample compute headroom.

At 3840x2160, the picture changes. Low settings yield 109.7 FPS, Medium drops to 89.3 FPS, High falls to 77.2 FPS, and Ultra bottoms out at 58.2 FPS. The 4K results show a much steeper drop-off as settings increase, with a 51.5 FPS gap between Low and Ultra. This is where the GPU finally becomes a more significant factor, as the pixel fill rate and shading demands at 4K Ultra begin to tax the RTX 5090. The 4K Low result of 109.7 FPS is still impressive, but the Ultra preset’s sub-60 FPS average indicates that owners seeking maximum fidelity at 4K will need to adjust settings or rely on upscaling technologies.

How This Combo Ranks

In the database of tested combinations for Rust, this pairing of the Intel Core i5-10400F and NVIDIA GeForce RTX 5090 ranks 337th out of 1,717 total combos. This places it in the top 19.6% of all tested systems, which is a strong result given the CPU’s age. The rank reflects the fact that the RTX 5090 carries the combo to high frame rates, but the i5-10400F prevents it from reaching the top tier. Combos with newer, higher-clocked processors paired with the RTX 5090 would likely occupy the upper echelons of this ranking.

The 337th rank confirms the RTX 5090’s brute force, as it compensates for the CPU’s limitations in Rust’s GPU-bound scenes. However, the rank also highlights the mismatch: a more balanced pairing, such as a higher-core-count 10th-gen or newer Intel chip, would likely push this combo into the top 100. The data shows that while the i5-10400F can sustain playable frame rates in Rust, it leaves significant performance on the table, particularly at 1080p and 1440p where the GPU is underutilized. For users with this CPU, upgrading the processor would yield a larger FPS gain than any GPU change, as the RTX 5090 is already operating well below its potential in most scenarios.