Microsoft Flight Simulator

# How This Combo Ranks

The Intel Core i5-9400 paired with the NVIDIA GeForce RTX 5090 lands at rank 317 out of 1,795 tested combos in Microsoft Flight Simulator. That places this configuration in the top 18% of all combinations evaluated, which is a strong showing for a pairing that mixes an older six-core CPU with a flagship-class GPU. The data indicates the RTX 5090 is doing the heavy lifting here—its percentile rank of 94 among all GPUs puts it well above the i5-9400's 50th percentile among CPUs. This creates an imbalanced pairing where the GPU is clearly the dominant component, but the combination still outperforms the vast majority of tested systems in this specific title.

Looking at the nearest rivals for context, the CPU's average benchmark score of 2,305 sits within 0.6% of several close competitors. The Intel Core i3-10305 and Core i3-1125G4 both score within 0.2% of the i5-9400, while the Intel Core i7-8809G is actually 0.6% faster. This tells us that the i5-9400 is functionally equivalent to a modern i3 in raw compute terms, yet the overall combo ranking benefits enormously from the RTX 5090's raw throughput. The GPU's average benchmark score of 84,306 places it just 0.1% ahead of the RTX 5090 D and 1.3% ahead of the AMD Radeon PRO W6600, confirming this is near the very top of the GPU hierarchy.

# FAQ

Q: Is this combination bottlenecked by the CPU?

A: Yes, particularly at lower resolutions. At 1080p, the difference between Low and Ultra settings is only 23.9 FPS (130.9 vs 107.0), which suggests the CPU is limiting the GPU's ability to stretch its legs. The RTX 5090 is capable of far higher frame rates, but the i5-9400's six cores and six threads cap the output.

Q: How does the i5-9400 compare to its closest rivals?

A: The i5-9400's average benchmark score of 2,305 is essentially tied with the Intel Core i3-10305 (2,300) and Core i3-1125G4 (2,299), both within 0.2% delta. The Intel Xeon E-2134 scores 2,295 (0.4% slower), while the Intel Core i7-8809G scores 2,319 (0.6% faster). These are all statistically equivalent performers.

Q: What is the best resolution for this combo?

A: The data suggests 1440p is the sweet spot. At 2560x1440 with High settings, the combo delivers 95.7 FPS, which is only 12.3 FPS less than 1080p High (108 FPS). Moving to 2160p High drops to 79.9 FPS, a further 15.8 FPS decline. The 1440p results offer a better balance between visual fidelity and frame rate.

Q: Does the RTX 5090's 32 GB of VRAM matter here?

A: Microsoft Flight Simulator is known for heavy texture streaming, and the RTX 5090's 32 GB of GDDR7 memory with 1.79 TB/s bandwidth ensures no memory-related stutters at any resolution tested. The memory subsystem is far beyond what this game requires, even at Ultra settings.

Q: How much performance does the Ultra preset cost over High?

A: Across all resolutions, the Ultra preset costs between 1.0 and 3.3 FPS compared to High settings. At 1080p, Ultra runs at 107.0 FPS versus 108 FPS on High—a negligible 0.9% drop. At 4K, Ultra runs at 81.1 FPS versus 79.9 FPS on High, which is actually faster due to measurement variance.

Q: Is this a future-proof combination?

A: The RTX 5090 is actively in production and represents the current flagship, while the i5-9400 is end-of-life with a 2018 release date. The CPU's 6 cores and 6 threads with a 4.10 GHz boost clock will likely become a growing bottleneck in future titles, but for Microsoft Flight Simulator specifically, the current data shows acceptable performance.

# Resolution Scaling

The measured FPS data reveals a clear pattern of diminishing returns as resolution increases, but with an unusual twist: the CPU bottleneck at 1080p is so pronounced that the scaling curve flattens more than expected. At Low settings, the combo delivers 130.9 FPS at 1080p, 119.7 FPS at 1440p (a 8.6% drop), and 107.5 FPS at 4K (a 17.9% drop from 1080p). This is a relatively gentle decline, suggesting the GPU has ample headroom and the CPU is the constraining factor even at 4K.

The High settings curve tells a similar story: 108 FPS at 1080p, 95.7 FPS at 1440p (11.4% lower), and 79.9 FPS at 4K (26.0% lower). The larger percentage drop from 1440p to 4K on High settings (16.5%) compared to Low settings (10.2%) indicates that as graphical load increases, the GPU starts to become more relevant, but the CPU still prevents the RTX 5090 from reaching its full potential.

Ultra settings show the most interesting behavior: 107 FPS at 1080p, 97.8 FPS at 1440p, and 81.1 FPS at 4K. The 1080p Ultra result is only 1 FPS lower than 1080p High, which strongly implies the CPU is the hard limit at that resolution. The RTX 5090's raw compute power (104.8 TFLOPS FP32) is simply not being utilized fully at 1080p because the i5-9400 cannot feed it data fast enough.

# Measured FPS Breakdown

At 1920x1080, the combo produces its highest raw frame rates. Low settings yield 130.9 FPS, Medium drops to 117.2 FPS, High lands at 108 FPS, and Ultra rounds out at 107 FPS. The gap between Low and Ultra is 23.9 FPS (18.3%), but the gap between High and Ultra is just 1 FPS—a clear sign that the Ultra preset's additional graphical features are nearly free at this resolution due to CPU limiting.

Moving to 2560x1440, the frame rates remain strong. Low settings produce 119.7 FPS, Medium 108.9 FPS, High 95.7 FPS, and Ultra 97.8 FPS. Interestingly, Ultra is 2.1 FPS faster than High at this resolution, which is within measurement variance but suggests the Ultra preset may be utilizing GPU resources differently. The drop from 1080p Low to 1440p Low is 11.2 FPS (8.6%), while the drop from 1080p High to 1440p High is 12.3 FPS (11.4%).

At 3840x2160, the combo still delivers playable frame rates across all settings. Low produces 107.5 FPS, Medium 95.9 FPS, High 79.9 FPS, and Ultra 81.1 FPS. Again, Ultra slightly outperforms High at 4K, which is anomalous but consistent with the 1440p results. The total range from Low to Ultra at 4K is 26.4 FPS, the largest spread of any resolution, indicating the GPU is finally becoming more of a limiting factor at 4K.

# Settings Recommendations

For players targeting maximum frame rates, the Low preset at 1080p delivers 130.9 FPS, which is the highest measured result in the entire dataset. However, Microsoft Flight Simulator is a visually demanding title where graphical fidelity contributes significantly to the experience, and sacrificing all visual quality for 23.9 FPS over Ultra is rarely worth it.

The data suggests that High settings provide the best balance of visual quality and performance across all resolutions. At 1080p, High runs at 108 FPS, which is smooth and only 1 FPS slower than Ultra. At 1440p, High delivers 95.7 FPS versus 97.8 FPS on Ultra—essentially identical, making High the smarter choice for reduced GPU load. At 4K, High runs at 79.9 FPS, which is within 1.2 FPS of Ultra.

The Medium preset also warrants consideration. At 1080p, it delivers 117.2 FPS, which is 9.2 FPS faster than High. At 1440p, Medium hits 108.9 FPS, a 13.2 FPS improvement over High. At 4K, Medium produces 95.9 FPS, a full 16 FPS faster than High. For users with high-refresh-rate displays at 1440p or 4K, Medium may be the more practical choice despite the visual compromises.

Given the CPU bottleneck, the Ultra preset is not recommended at any resolution. The performance cost over High is negligible (0.9% at 1080p, -2.2% at 1440p, -1.5% at 4K), but it also does not provide a meaningful frame rate advantage, and the additional GPU load serves no practical purpose when the CPU is already the limiting factor.

# CPU Role

The Intel Core i5-9400 is a Coffee Lake Refresh part with 6 cores and 6 threads, base clock of 2.90 GHz, and boost clock of 4.10 GHz. It has 9 MB of shared L3 cache, with 64 KB L1 and 256 KB L2 per core. This is a locked multiplier CPU (no overclocking) on the Intel Socket 1151 platform, supporting dual-channel DDR4 memory with 42.7 GB/s bandwidth.

In Microsoft Flight Simulator, which is known to be heavily CPU-dependent for its flight model and world simulation, the i5-9400's six physical cores without hyper-threading show their age. The Cinebench R23 multi-core score of 7,969 and single-core score of 1,125 place this CPU at the 50th percentile of all CPUs, which is middling. The 4.10 GHz boost clock helps single-threaded performance, and the game's data shows the combo still achieves respectable frame rates, but the CPU's limitations are most evident in the small FPS differences between High and Ultra settings.

The 65W TDP and 14 nm process node indicate this is a modest power draw part, but its end-of-life production status and 2018 release date mean it lacks modern efficiency features. The RTX 5090, by contrast, is a 575W card on a 5 nm process with 92,200 million transistors, representing the absolute modern of GPU technology. This pairing is fundamentally mismatched—the GPU is operating at a fraction of its capability in CPU-bound scenarios, particularly at 1080p where the difference between Low and Ultra is only 23.9 FPS.

The benchmark data shows the i5-9400's average score of 2,305 is nearly identical to the Intel Core i3-10305 (2,300, 0.2% delta), meaning this "i5" performs like a modern i3. For Microsoft Flight Simulator specifically, the 6-core/6-thread configuration is sufficient to avoid the worst stutters, but players upgrading from this CPU would likely see substantial FPS gains even with the same RTX 5090, as the GPU clearly has substantial untapped headroom across all tested resolutions and settings.