Rust

The Intel Core i5-9400 paired with the AMD Radeon RX 7900 XT presents a lopsided pairing in Rust, where the GPU's raw power is frequently constrained by the older six-core processor. The recorded data shows that this combination is highly capable at 1080p and 1440p, delivering smooth frame rates across nearly all presets, but it struggles to maintain a consistent 60 FPS at 4K on higher settings. Benchmark results indicate that the system is best suited for high-refresh-rate 1440p gaming, where it can push well beyond the 60 FPS threshold even at Ultra settings.

Measured FPS Breakdown

At 1920x1080, the combination delivers its strongest performance. The average frame rates across all four presets comfortably exceed the 60 FPS playable threshold. At Low settings, the system achieves an average of 140.7 FPS, which is the highest recorded figure for this pairing. Moving to Medium, the average drops to 123.8 FPS, still a very strong result. High settings yield an average of 114.4 FPS, while Ultra settings produce 105.6 FPS. The scaling between Low and Ultra at this resolution is a 35.1 FPS drop, indicating that the GPU has ample headroom and the CPU is not the primary limiting factor.

At 2560x1440, performance remains robust but shows a clearer impact from the increased pixel count. Low settings average 124.2 FPS, which is only 16.5 FPS lower than the 1080p Low result. Medium settings average 105.8 FPS, while High settings deliver 92.4 FPS. Ultra settings at 1440p average 70.7 FPS, which is above the 60 FPS target but represents a significant step down from the 105.6 FPS seen at 1080p Ultra. The spread from Low to Ultra at this resolution is 53.5 FPS, showing that the GPU is beginning to work harder as resolution increases.

At 3840x2160, the system's limitations become apparent. Low settings average 101.1 FPS, which is still a playable result. Medium settings drop to 67.6 FPS, barely clearing the 60 FPS threshold. High settings fall to 59 FPS, just under the playable mark, and Ultra settings average only 44.7 FPS, which is not suitable for smooth gameplay. The data shows a steep decline from Low to Ultra at 4K, with a 56.4 FPS difference, confirming that the GPU is heavily loaded at this resolution while the CPU struggles to keep up with the frame pacing demands.

CPU and GPU Roles

The benchmark data reveals a clear shift in component importance depending on resolution. At 1920x1080, the CPU plays a dominant role. The Intel Core i5-9400, with its 6 cores and 6 threads, becomes the bottleneck as frame rates climb past 120 FPS. The evidence is in the relatively small performance gap between Low and Ultra settings: only a 25% difference in average FPS. This suggests that the CPU is limiting the frame rate ceiling, preventing the RX 7900 XT from fully stretching its legs.

At 2560x1440, the balance shifts toward the GPU. The performance gap between Low and Ultra widens to 43% (from 124.2 to 70.7 FPS), indicating that the graphics card is now the primary driver of performance differences. The CPU still matters, but it is no longer the sole constraint. The RX 7900 XT's 20 GB of GDDR6 memory and 800.0 GB/s bandwidth are sufficient for the higher pixel count, and the data shows that the GPU is scaling more predictably with settings changes.

At 3840x2160, the GPU becomes the overwhelming bottleneck. The performance drop from Medium to Ultra is 22.9 FPS (from 67.6 to 44.7), and the difference between Low and Ultra is 56.4 FPS. This behavior indicates that the RX 7900 XT is fully saturated at 4K, and the CPU's role is diminished. The i5-9400's 9 MB of shared L3 cache and 42.7 GB/s memory bandwidth are adequate for feeding the GPU at this resolution, but the GPU's raw compute power (51.48 TFLOPS FP32) is not enough to maintain high frame rates at 4K Ultra in Rust.

Similar Performance Alternatives

Looking at the nearest rivals for the CPU, the Intel Core i5-9400 has an average benchmark score of 2254. The closest alternatives are the Intel Core i7-1068NG7, which scores 2259 (0.2% higher), and the Intel Core i3-10305, which scores 2264 (0.4% higher). These CPUs would deliver nearly identical frame pacing in Rust, meaning any of them would produce similar results when paired with the RX 7900 XT. The AMD Ryzen 5 PRO 1500, with a score of 2246 (0.4% lower), would also behave comparably, though it may show slightly lower minimum frame rates in CPU-bound scenarios.

For the GPU, the AMD Radeon RX 7900 XT has an average benchmark score of 13745. The nearest rival is the AMD Radeon RX 9070 XT, which scores 13543 (1.5% lower). This means the RX 9070 XT would deliver almost identical frame rates in Rust, likely within 1-2 FPS of the recorded numbers. The AMD Radeon 660M (score 13812, 0.5% higher) and the NVIDIA RTX A2000 Mobile (score 13821, 0.5% higher) are also close, but these are mobile or integrated parts that would not be realistic desktop substitutes. The AMD Radeon RX 570X (score 13871, 0.9% higher) is another desktop option that would perform similarly, though its architecture is older.

The Verdict

The verdict by resolution is clear. At 1920x1080, this PC can run Rust at all four settings presets with average frame rates above 60 FPS. The best experience is at Ultra settings, where the average is 105.6 FPS, providing a smooth and visually rich experience. At 2560x1440, the system also clears 60 FPS at every preset, with Ultra averaging 70.7 FPS. This is the sweet spot for this combination, offering high visual fidelity and smooth gameplay.

At 3840x2160, the system is only playable at Low and Medium settings. Low averages 101.1 FPS, while Medium averages 67.6 FPS, both above the 60 FPS threshold. High settings fall to 59 FPS, which is a marginal miss, and Ultra averages 44.7 FPS, which is not playable. The recommended 4K setting is Medium, as it provides the best balance of visual quality and performance, with an average FPS of 67.6. For users who prioritize frame rate over visuals, Low at 4K is also a valid choice.

How This Combo Ranks

In the database of tested combinations, this pairing ranks 1185 out of 3723 total combos for Rust. This places it in the top 31.8% of all tested systems, which is a solid result given the CPU's age. The ranking reflects that the RX 7900 XT is a high-end GPU, but the i5-9400 holds the system back from reaching the upper echelons of the leaderboard. Combos with newer, higher-core-count CPUs would likely rank higher, as Rust is known to be CPU-intensive in certain scenarios. However, this rank is still respectable, indicating that the system is well above average for gaming performance in this title.

FAQ

Q: Can this PC run Rust at 60 FPS on 1080p Ultra settings?

A: Yes. The recorded average FPS at 1920x1080 Ultra is 105.6, which is well above the 60 FPS playable threshold.

Q: What is the best settings preset for 4K gaming with this combo?

A: Medium is the recommended choice at 3840x2160, as it delivers an average of 67.6 FPS. Low is also playable at 101.1 FPS, but High (59 FPS) and Ultra (44.7 FPS) fall below the 60 FPS target.

Q: How does the Intel Core i5-9400 compare to its nearest CPU rivals?

A: The i5-9400 has an average score of 2254. The Intel Core i7-1068NG7 scores 2259 (0.2% higher), the Intel Core i3-10305 scores 2264 (0.4% higher), and the AMD Ryzen 5 PRO 1500 scores 2246 (0.4% lower). These differences are negligible in real-world gaming.

Q: Is the AMD Radeon RX 7900 XT a good match for this CPU?

A: The data shows it is a capable pairing at 1080p and 1440p, but the CPU limits performance at lower resolutions. At 4K, the GPU becomes the bottleneck, and the pairing is less effective.

Q: What is the frame rate difference between 1080p Low and 1440p Low?

A: At 1080p Low, the average FPS is 140.7. At 1440p Low, it drops to 124.2, a 16.5 FPS difference.

Q: Does this combo support ray tracing?

A: The AMD Radeon RX 7900 XT has 84 ray accelerators and supports DirectX 12 Ultimate (12_2), but the measured FPS data in the database does not include ray tracing results for Rust, so no definitive performance claim can be made.