Thief

The Intel Core i5-9400 paired with the NVIDIA GeForce RTX 5090 ranks 887th out of 1,642 tested combinations in Thief, placing it in the lower-middle portion of the database. This rank reflects a significant bottleneck: the RTX 5090, which sits in the 94th percentile of all GPUs, is being held back by a six-core CPU that launched in 2018 and now sits at the 50th percentile of all processors. The data indicates that while the GPU is capable of far higher frame rates, the i5-9400’s architectural limitations prevent the combo from climbing higher in the rankings.

How This Combo Ranks

The combo’s 887th-place finish out of 1,642 tested combinations suggests a fundamental imbalance. The RTX 5090 is a top-tier card, but the i5-9400 is a mid-range part from an older generation. The CPU’s 6 cores and 6 threads, with a base clock of 2.90 GHz and boost of 4.10 GHz, are sufficient for many titles, but Thief’s engine appears sensitive to single-thread performance. The i5-9400’s average benchmark score of 2,305 places it just 0.2% ahead of the Intel Core i3-10305 and 0.2% ahead of the Intel Core i3-1125G4, while being 0.6% behind the Intel Core i7-8809G. These rivals are all lower-tier or mobile parts, underscoring that the CPU is not a high-end performer. In practice, the data shows the combo achieving frame rates that are respectable but far from the maximum potential of the RTX 5090.

GPU Role

The NVIDIA GeForce RTX 5090 is the dominant component in this pairing, featuring a massive 32 GB of GDDR7 memory on a 512-bit bus, delivering 1.79 TB/s of bandwidth. Its base clock of 2017 MHz and boost clock of 2407 MHz are backed by 21,760 shading units, and the card’s 104.8 TFLOPS of FP32 compute power is extraordinary. In Thief, however, the GPU’s role is constrained by the CPU. At 1080p, the GPU is not the limiting factor; the CPU is. This is evident in the scaling pattern: moving from 1080p to 1440p to 4K does not produce the dramatic FPS drops one would expect from a GPU-bound scenario. The RTX 5090’s 94th percentile ranking among all GPUs, with an average benchmark score of 84,306, places it just 0.1% ahead of the RTX 5090 D and 0.2% ahead of the RTX 5050 Mobile, but these are synthetic scores. In a real game like Thief, the CPU bottleneck means the GPU’s immense resources are underutilized, especially at lower resolutions.

Resolution Scaling

The measured FPS data reveals a clear pattern of CPU limitation. At 1080p with High settings, the combo delivers 99.3 FPS, but at 1440p High, it drops to 86 FPS, and at 4K High, it falls to 70.7 FPS. The drop from 1080p to 1440p is 13.3 FPS, and from 1440p to 4K is another 15.3 FPS. These are relatively modest declines for a game like Thief, which is not particularly demanding by modern standards. If the GPU were the primary constraint, the 4K result would be far lower relative to 1080p, given the fourfold increase in pixel count. Instead, the scaling suggests that at 1080p, the CPU is maxed out, and as resolution increases, the GPU takes on more work, but the CPU still holds the combo back. The gap between Low and Ultra settings at each resolution also indicates this: at 1080p, Low delivers 117.3 FPS while Ultra delivers 93.4 FPS, a difference of 23.9 FPS. At 4K, the same comparison shows 86.5 FPS versus 72.7 FPS, a difference of 13.8 FPS, which means the GPU is able to flex more at higher resolutions, but the CPU remains the bottleneck.

Settings Recommendations

The measured rows suggest that the Medium preset offers the best balance for this combo. At 1080p, Medium produces 105.4 FPS, which is notably higher than High’s 99.3 FPS and Ultra’s 93.4 FPS, while only trailing Low’s 117.3 FPS. The visual quality improvement from Low to Medium is substantial, and the FPS cost is relatively small. At 1440p, Medium delivers 96.8 FPS, again a strong result that is only 9 FPS behind Low but 10.8 FPS ahead of Ultra. At 4K, Medium yields 80.9 FPS, which is playable and only 5.6 FPS behind Low, while High drops to 70.7 FPS and Ultra to 72.7 FPS. The data indicates that Medium is the sweet spot: it avoids the sharp FPS penalties of High and Ultra while providing a better experience than Low. For users with high-refresh-rate 1080p monitors, Low at 117.3 FPS might be tempting, but the visual fidelity loss is likely not worth the 11.9 FPS gain over Medium. Conversely, at 4K, the drop from Medium to High is 10.2 FPS, which outweighs any visual benefit given the CPU bottleneck.

Measured FPS Breakdown

At 1920x1080, the combo achieves its highest frame rates. Low settings produce 117.3 FPS, Medium 105.4 FPS, High 99.3 FPS, and Ultra 93.4 FPS. The spread from Low to Ultra is 23.9 FPS, indicating that the CPU is the primary limiter, as the GPU can handle the lower resolutions with ease. The 1080p results are all above 90 FPS, which is smooth, but the ceiling is clearly set by the i5-9400 rather than the RTX 5090.

At 2560x1440, the frame rates remain high but begin to show more GPU involvement. Low delivers 105.8 FPS, Medium 96.8 FPS, High 86 FPS, and Ultra 82.9 FPS. The drop from Low to Ultra is 22.9 FPS. Notably, the 1440p Low result is higher than the 1080p High result, which confirms that the GPU is not strained at 1440p. The CPU still dictates the upper bound, but the gap between settings narrows slightly compared to 1080p, suggesting that the GPU is starting to contribute more to the overall performance.

At 3840x2160, the frame rates drop further but remain playable. Low produces 86.5 FPS, Medium 80.9 FPS, High 70.7 FPS, and Ultra 72.7 FPS. The anomaly here is that High is slightly lower than Ultra, a difference of 2 FPS, which is within measurement variance. The spread from Low to Ultra is 13.8 FPS, much narrower than at 1080p. This indicates that at 4K, the GPU is finally becoming a more significant factor, but the CPU still prevents the card from reaching its full potential. The 4K results are all above 70 FPS, which is respectable, but they are far below what the RTX 5090 could achieve with a more capable processor. The data clearly shows that this combo is CPU-limited in Thief, and any upgrade to the processor would yield substantial gains in 1080p and 1440p performance, while 4K would see more modest improvements.