Roblox

The Intel Core i5-9400 paired with the AMD Radeon RX 7900 XTX is a lopsided pairing for Roblox, where the 2018 six-core processor becomes the primary constraint at lower resolutions. The i5-9400 operates with 6 cores and 6 threads at a base clock of 2.90 GHz, boosting to 4.10 GHz, which is sufficient for the game's thread utilization but bottlenecks the GPU when frame rates climb. The CPU sits at the 50th percentile among all tested processors, with an average benchmark score of 2305; its nearest rival, the Intel Core i3-10305, scores 2300 (0.2% faster), while the Intel Xeon E-2134 trails at 2295 (0.4% slower). This mid-pack CPU performance means that while the RX 7900 XTX (which sits at the 85th GPU percentile with an average score of 44019) can render Roblox at extreme speeds, the i5-9400 cannot feed it enough data to sustain those rates at 1080p.

CPU Role — cores, clocks, and how they relate to this game's results

Roblox is a sandbox title that relies heavily on single-thread performance for its physics and scripting, but the data shows that the i5-9400's six physical cores are engaged enough to matter. With 6 threads and a boost clock of 4.10 GHz, the CPU delivers a Cinebench R23 single-core score of 1125 and a multi-core score of 7969, placing it squarely in the middle of the desktop CPU landscape. In this combo, the CPU is the limiting factor at 1080p: at Low settings, the average frame rate is 555 FPS, but at Ultra settings it drops to 382.5 FPS, a 31% reduction that reflects the CPU's inability to push higher draw calls rather than GPU limits.

The RX 7900 XTX, by contrast, is a flagship RDNA 3.0 part with 6144 shading units and a boost clock of 2498 MHz, capable of 61.39 TFLOPS FP32 throughput. Its 24 GB of GDDR6 memory on a 384-bit bus provides 960.0 GB/s of bandwidth, far beyond what Roblox requires. The GPU's average benchmark score of 44019 puts it 0.8% ahead of the NVIDIA GeForce RTX 4090 Mobile (43667) and 1.6% ahead of the NVIDIA Quadro M6000 (43313), but those comparisons are moot when the CPU caps the frame rate. At 4K Ultra, the combo still manages 144.5 FPS, indicating that at higher resolutions the GPU becomes the bottleneck, but at 1080p the CPU's 6-thread ceiling is evident.

The i5-9400's memory bandwidth of 42.7 GB/s (DDR4 dual-channel) is another constraint; the CPU sits at the 50th percentile, and its nearest rivals are all within 0.6% of its score, showing that this is a crowded mid-range field. For Roblox, the CPU's 9 MB shared L3 cache helps with the game's asset streaming, but the lack of hyper-threading (6 threads, not 12) means that background tasks or complex scenes with many players can cause frame dips. The data shows that at 1440p, the combo scales to 391.4 FPS at Low and 252.4 FPS at Ultra, a 35% drop, which is a smaller penalty than at 1080p (31% vs. 31% — actually identical), suggesting the CPU is still the primary limit even as resolution increases.

FAQ — 4-6 Q&A pairs answerable from FACT PACK data

Q: Is the Intel Core i5-9400 a bottleneck for the AMD Radeon RX 7900 XTX in Roblox?

A: Yes, at 1080p and 1440p. The data shows that at 1080p Low, the combo achieves 555 FPS, but at 4K Low it drops to 217.6 FPS, a 61% reduction. Since the GPU is far more powerful (85th GPU percentile vs. 50th CPU percentile), the CPU's 6 cores and 4.10 GHz boost clock limit the maximum frame rate, especially at lower resolutions where the GPU is not fully utilized.

Q: How does the i5-9400 compare to its direct rivals in synthetic benchmarks?

A: The i5-9400 has an average benchmark score of 2305, placing it 0.2% ahead of the Intel Core i3-10305 (2300) and 0.2% ahead of the Intel Core i3-1125G4 (2299). It is 0.4% faster than the Intel Xeon E-2134 (2295) but 0.6% slower than the Intel Core i7-8809G (2319). These deltas are negligible, indicating the i5-9400 is a typical mid-range performer.

Q: What is the best resolution for this combo to avoid CPU limitations?

A: The data suggests 4K is where the GPU becomes the bottleneck. At 4K Ultra, the combo delivers 144.5 FPS, while at 1080p Ultra it reaches 382.5 FPS. The gap between Low and Ultra at 4K is 73.1 FPS (217.6 vs. 144.5), whereas at 1080p the gap is 172.5 FPS (555 vs. 382.5), showing that the CPU's impact diminishes as resolution increases.

Q: Does the RX 7900 XTX's performance justify its pairing with this CPU?

A: No, from a balance perspective. The GPU scores 44019 on average, sitting at the 85th percentile, while the CPU is at the 50th percentile. In Roblox, this results in a combo rank of 305 out of 1800 tested combinations, meaning 1495 other pairings perform better. The GPU is capable of far more, but the CPU holds it back at lower resolutions.

Q: What frame rates can a user expect at 1440p with this combo?

A: At 2560x1440, the average FPS ranges from 391.4 (Low) to 252.4 (Ultra), with Medium at 356.6 and High at 314.8. These numbers are well above 144 Hz monitors, but the 39% difference between Low and Ultra indicates the CPU is still the limiting factor, as the GPU would normally show a larger spread with settings changes.

Q: How does the combo rank in Roblox compared to all tested configurations?

A: The combo ranks 305th out of 1800 combinations, placing it in the top 17% of all tested pairings. Given that the GPU alone is at the 85th percentile, the CPU's 50th percentile position drags the overall rank down, confirming that this is a CPU-limited configuration for Roblox.

Resolution Scaling — how FPS drops from 1080p to 4K and what it says about the limiting component

The measured FPS reveals a clear pattern of CPU limitation at lower resolutions. At 1080p Low, the combo hits 555 FPS, but at 4K Low it drops to 217.6 FPS — a 60.8% reduction. At 1080p Ultra, the frame rate is 382.5 FPS, falling to 144.5 FPS at 4K Ultra, a 62.2% reduction. These similar percentage drops across settings indicate that the CPU is the consistent bottleneck, as the GPU's workload scales with resolution but the CPU's ability to issue draw calls does not.

At 1440p, the frame rates are 391.4 FPS (Low) and 252.4 FPS (Ultra), showing a 35.5% reduction from Low to Ultra. This is a smaller drop than at 1080p (31% — actually 30.9%), but the absolute numbers are still high enough to suggest the CPU is not fully saturated. At 4K, the GPU begins to take over: the difference between Low (217.6 FPS) and Ultra (144.5 FPS) is 33.6%, which is closer to what a GPU-bound scenario would show, but the i5-9400 still limits the maximum frame rate to under 220 FPS even at Low settings.

The scaling data shows that moving from 1080p to 1440p reduces FPS by about 29% (555 to 391.4 at Low), while moving from 1440p to 4K reduces FPS by 44% (391.4 to 217.6). This non-linear scaling is characteristic of a system where the CPU becomes less of a constraint as resolution increases, but the GPU is never fully utilized until 4K. The RX 7900 XTX, with its 960.0 GB/s memory bandwidth, is capable of much higher frame rates at 4K, but the i5-9400's 6-thread architecture cannot keep up with the game's update loop.

How This Combo Ranks — use comboRankInGame vs other tested combos

The combo ranks 305th out of 1800 tested combinations in Roblox, placing it in the 83rd percentile of all tested pairings. This is a surprisingly low rank given the GPU's performance, as the RX 7900 XTX alone sits at the 85th GPU percentile. The ranking indicates that the i5-9400 is a significant drag: 1495 other CPU-GPU pairings produce higher average frame rates in Roblox, despite many of those using weaker GPUs.

The rank discrepancy is explained by the CPU's benchmark position. The i5-9400's average score of 2305 is only 0.2% above the Intel Core i3-10305 and 0.2% above the Intel Core i3-1125G4, but it is 0.6% below the Intel Core i7-8809G. In Roblox, which is CPU-sensitive at high frame rates, this mid-pack processor prevents the GPU from reaching its potential. The combo's rank of 305 suggests that users with this pairing will see excellent absolute FPS (over 144 at 4K Ultra), but relative to other combos, it underperforms because the CPU cannot sustain the frame rates that the GPU could otherwise deliver.

At 1080p, the combo's average FPS across all settings is 484.05 (555, 530.2, 468.5, 382.5), but the rank is dragged down by the fact that many other combos with faster CPUs (even with slower GPUs) can achieve higher minimum frame rates in Roblox's CPU-bound scenes. The data shows that the combo is not in the top 10% of pairings, despite the GPU being in the top 15% individually. This is a textbook example of a CPU bottleneck, where the processor's 50th percentile performance caps the system's overall capability.

Measured FPS Breakdown — resolution by resolution, settings by settings, exact numbers

At 3840x2160, the combo delivers an average of 178.6 FPS at High settings, 217.6 FPS at Low, 203 FPS at Medium, and 144.5 FPS at Ultra. The spread from Low to Ultra is 73.1 FPS, a 33.6% reduction. These numbers show that even at 4K, the system is not entirely GPU-bound, as a fully GPU-limited scenario would show a wider gap between Low and Ultra (the GPU's fill rate would cause a larger drop). The 217.6 FPS at Low indicates that the CPU is still the limiting factor, as the RX 7900 XTX could theoretically render Roblox at much higher frame rates if the CPU could feed it.

At 2560x1440, the average FPS is 314.8 at High, 391.4 at Low, 356.6 at Medium, and 252.4 at Ultra. The drop from Low to Ultra is 139 FPS, a 35.5% reduction. The 391.4 FPS at Low is the highest frame rate at this resolution, but it is still 29.5% lower than the 1080p Low result of 555 FPS, showing that resolution scaling has a significant impact even with a powerful GPU. The 1440p results indicate that the CPU is still the primary bottleneck, as the GPU's compute headroom is not being fully utilized.

At 1920x1080, the combo reaches 468.5 FPS at High, 555 FPS at Low, 530.2 FPS at Medium, and 382.5 FPS at Ultra. The 555 FPS at Low is the highest measured value for this combo, and the 172.5 FPS difference between Low and Ultra (31.1% reduction) confirms that the i5-9400 is the limiting component. The CPU's 6 threads and 4.10 GHz boost clock cannot push beyond this threshold, even though the RX 7900 XTX has the raw power to render at much higher rates. The 1080p results are the clearest evidence of the CPU bottleneck, as the frame rates plateau around 555 FPS regardless of the GPU's capabilities.