Fortnite

Fortnite with an Intel Core i5-9400 and an NVIDIA GeForce RTX 4090 presents a stark study in bottlenecking. The data shows a GPU that is clearly capable of massive frame rates being held back by a six-core, six-thread CPU from 2018. The benchmark results indicate that while the RTX 4090 dominates at higher resolutions, the Core i5-9400’s limitations become increasingly apparent as resolution drops, ultimately capping performance in a way that leaves significant performance on the table for esports-focused play.

Resolution Scaling

The frame rate scaling across resolutions tells a clear story about where the system’s limits lie. At 4K with High settings, the combo averages 86.5 FPS. Dropping to 1440p High increases that to 166.5 FPS, a substantial 92.5% jump that shows the GPU still has headroom. Moving from 1440p to 1080p High yields 232 FPS, which is a 39.3% increase over the 1440p result. This scaling pattern—large gains from 4K to 1440p, but smaller gains from 1440p to 1080p—is the classic signature of a CPU bottleneck beginning to form.

The trend becomes even more pronounced when looking at the Low settings preset. At 4K Low, the system produces 158.1 FPS. At 1440p Low, it hits 248 FPS, a 56.9% improvement. However, moving to 1080p Low only nets 292.9 FPS, a mere 18.1% increase over the 1440p figure. If the GPU were the sole limiting factor, the jump to 1080p would be much larger. The data suggests that at 1080p Low, the Core i5-9400 is nearly saturated, preventing the RTX 4090 from stretching its legs fully. The scaling from 4K to 1440p is massive because the GPU is still the primary constraint at those higher pixel counts; the scaling from 1440p to 1080p compresses because the CPU becomes the wall.

GPU Role

The NVIDIA GeForce RTX 4090 is an absolute powerhouse on paper, and the benchmark results confirm its raw capability. It features 24 GB of GDDR6X memory on a 384-bit bus, providing 1.01 TB/s of bandwidth. The GPU’s boost clock is listed at 2520 MHz. This hardware combination is designed to obliterate any modern game at high resolutions. In Fortnite, this is evident in the 4K results, where the GPU is clearly the star of the show. The difference between 4K Low (158.1 FPS) and 4K High (86.5 FPS) shows the GPU’s workload scaling with settings. The GPU’s 82.58 TFLOPS of FP32 compute and 1,290.2 GTexel/s texture rate are massive numbers that would typically suggest frame rates far beyond what this combo achieves at 1080p.

However, the GPU’s role here is paradoxical. It is so powerful that it is rarely the limiting factor except at 4K with higher settings. The jump from 4K Ultra (56.8 FPS) to 4K High (86.5 FPS) is a 52.3% increase, and 4K Medium (115.6 FPS) further shows the GPU scaling with graphical load. The fact that the GPU can push 292.9 FPS at 1080p Low proves it has the headroom to go much higher, but the CPU prevents it from doing so. The RTX 4090’s launch MSRP is 1,599 USD, and in this pairing, a significant portion of that investment is left unused at lower resolutions.

CPU Role

The Intel Core i5-9400 is a 6-core, 6-thread processor from the Coffee Lake Refresh generation. It has a base clock of 2.90 GHz and a boost clock of 4.10 GHz. Its Cinebench R23 multi-core score is 7969, and single-core is 1125. In the context of modern CPUs, this processor sits at the 50th percentile of all CPUs, making it an average performer. Its nearest rivals include the Intel Core i3-10305 and Core i3-1125G4, with average scores of 2300 and 2299, respectively, showing just how close it is to lower-tier parts in synthetic tests.

In Fortnite, the CPU’s role is to feed the GPU with draw calls and game logic. The data shows this is where the bottleneck lies. At 1080p, the CPU is struggling to keep up. The difference between 1080p Medium (256.3 FPS) and 1080p Low (292.9 FPS) is only 14.3%, which is far smaller than the GPU’s potential headroom suggests it should be. The CPU’s 6 threads are simply not enough to fully utilize the RTX 4090’s massive shading power at lower resolutions. The 9 MB of shared L3 cache and dual-channel DDR4 memory support at 42.7 GB/s are also modest by today’s standards, further limiting the processor’s ability to feed the GPU quickly. The data indicates that the CPU is the primary constraint on frame rates at 1080p, effectively capping performance in the high-200s range.

Measured FPS Breakdown

At 1920x1080, the system delivers its highest frame rates. Low settings produce an average of 292.9 FPS, while Medium yields 256.3 FPS. High settings drop to 232 FPS, and Ultra settles at 172.9 FPS. The gap between Low and Ultra is 120 FPS, showing that the GPU can still handle the increased graphical load, but the CPU’s influence is clear—even at Low, the frame rate does not approach the GPU’s theoretical maximum.

Moving to 2560x1440, the frame rates remain high but begin to scale more predictably with GPU load. Low settings average 248 FPS, Medium hits 213.1 FPS, and High produces 166.5 FPS. Ultra at 1440p drops to 111.3 FPS. The scaling from Low to Ultra at 1440p is a 55.1% reduction, which is more consistent with a GPU-bound scenario compared to the 1080p results.

At 3840x2160, the GPU takes over as the primary bottleneck. Low settings average 158.1 FPS, Medium 115.6 FPS, and High 86.5 FPS. Ultra settings at 4K drop the average to 56.8 FPS. This is where the RTX 4090’s true power is on display, as the frame rates are still highly playable at 4K on high settings, but the CPU is no longer the limiting factor. The 4K Ultra result of 56.8 FPS is the lowest in the dataset, but it is also the most GPU-intensive scenario.

How This Combo Ranks

Within the benchmark database, this specific CPU-GPU combination holds a combo rank of 140 out of 1564 tested combinations. This places it in the top 9% of all tested combos for Fortnite, which is impressive on the surface. However, this ranking is heavily influenced by the GPU’s sheer power, which carries the combo to high absolute frame rates. The data suggests that the ranking would be significantly higher if the CPU were not holding the GPU back.

The ranking also implies that there are 139 other combos that perform better. Given the RTX 4090’s position at the 91st percentile of all GPUs and its average benchmark score of 66473, it is clear that pairing it with a more modern, higher-thread-count CPU would yield a much better rank. The Core i5-9400’s position at the 50th percentile of CPUs means that a large portion of the market has more capable processors, and many of those likely pair with the RTX 4090 to achieve higher frame rates in Fortnite. The combo’s rank of 140 reflects the GPU’s dominance, but it also highlights the wasted potential of the CPU pairing.

FAQ

Q: Is the Intel Core i5-9400 a bottleneck for the RTX 4090 in Fortnite?

A: Yes, the data strongly indicates this. At 1080p, the frame rate gains from lowering settings are much smaller than expected, suggesting the CPU is limiting performance. The 1080p Low average is 292.9 FPS, but this is only 14.3% higher than 1080p Medium, showing that the CPU cannot keep up with the GPU’s demands at lower resolutions.

Q: What is the best resolution to use with this combo?

A: The data shows the system scales well up to 1440p. At 1440p High, it averages 166.5 FPS, which is excellent. At 4K, the system is more balanced, with 86.5 FPS on High, but the CPU bottleneck is less severe. For competitive play, 1080p Low at 292.9 FPS is the highest frame rate, but the CPU is still the limiting factor.

Q: How does this combo rank compared to other tested systems?

A: It ranks 140th out of 1564 tested combos, placing it in the top 9%. This is a strong ranking, but it is likely carried by the RTX 4090’s raw power rather than the CPU’s contribution.

Q: Is the performance at 4K playable?

A: Yes, the 4K results are playable. High settings average 86.5 FPS, Medium 115.6 FPS, and Low 158.1 FPS. Even Ultra at 4K produces 56.8 FPS, which is acceptable for less demanding players. The system is well-suited for 4K gaming with this combo.

Q: How does the CPU’s synthetic benchmark performance relate to its in-game results?

A: The Core i5-9400 has a Cinebench R23 multi-core score of 7969 and sits at the 50th percentile of all CPUs. This average synthetic performance aligns with its in-game behavior, where it struggles to feed the GPU at high frame rates. Its nearest rivals, such as the Core i3-10305, have nearly identical average scores, indicating similar potential limitations.

Q: What is the impact of the RTX 4090’s large VRAM and high clocks?

A: The 24 GB of GDDR6X memory and 2520 MHz boost clock ensure the GPU never runs out of memory or compute resources in Fortnite. The data shows that the GPU is not the limiting factor at 1080p, as frame rates plateau due to the CPU, not the GPU’s specifications. The GPU’s capabilities are only fully utilized at 4K, where it delivers 86.5 FPS on High settings.