Roblox

Roblox is a sandbox title where the CPU and GPU play very different roles depending on the resolution and settings selected. The Intel Core i5-9400 is a 6-core, 6-thread desktop processor from the Coffee Lake Refresh generation, built on Intel's 14 nm process. It has a base clock of 2.90 GHz and a boost clock of 4.10 GHz, with a 65 W TDP. The processor's cache layout includes 64 KB of L1 cache per core, 256 KB of L2 per core, and 9 MB of shared L3 cache. Its memory bandwidth is rated at 42.7 GB/s over a dual-channel DDR4 interface, and it connects to the rest of the system via PCIe Gen 3 with 16 lanes from the CPU.

In synthetic CPU benchmarks, the i5-9400 scores 935 points in Cinebench R23 single-core and 6,629 points in multi-core. Its Geekbench scores are 1,389 single-core and 5,141 multi-core. The processor sits at the 47th percentile when compared to all CPUs in the database, with an average benchmark score of 2,254. Its nearest rivals in terms of average score include the Intel Core i7-1068NG7 at 2,259 (a delta of -0.2%), the Intel Core i7-10710U at 2,248 (delta of +0.3%), and the AMD Ryzen 5 PRO 1500 at 2,246 (delta of +0.4%). These are all essentially neck-and-neck scores, indicating that the i5-9400 is positioned in a dense cluster of mid-range processors from its era.

For a game like Roblox, which is known to be more dependent on single-threaded performance than on raw multi-core throughput, the i5-9400's single-core score of 935 in Cinebench R23 suggests that it is adequate but not exceptional. The data shows that at 1080p resolution with Low settings, the combo produces 554 FPS, which is the highest average measured across all tested configurations. This high frame rate indicates that the CPU is capable of feeding the GPU enough data at lower resolutions, but the gap between Low and Ultra settings at 1080p is significant: 554 FPS versus 420 FPS, a difference of 134 FPS. This delta suggests that while the CPU is not a hard bottleneck at 1080p, the increased draw calls and physics calculations at Ultra settings do eat into the headroom that the processor has.

The NVIDIA GeForce RTX 4080 is the dominant component in this pairing. This GPU is built on the Ada Lovelace architecture with a 5 nm process from TSMC, featuring 45,900 million transistors on a 379 mm² die. It has a base clock of 2205 MHz and a boost clock of 2505 MHz, with memory running at 1400 MHz (22.4 Gbps effective). The card comes with 16 GB of GDDR6X memory on a 256-bit bus, providing 716.8 GB/s of bandwidth. Its compute resources include 9,728 shading units, 304 TMUs, and 112 ROPs, along with 76 RT cores and 304 tensor cores. The RTX 4080 achieves 48.74 TFLOPS of FP32 performance and has a 320 W TDP, requiring a triple-slot cooler and a 16-pin power connector, with a suggested PSU of 700 W.

In GPU benchmarks, the RTX 4080 scores 34,457 in Passmark G3D and 20,671 in Passmark GPU Compute. Its 3DMark Steel Nomad DX12 score is 6,567, and it posts Geekbench scores of 214,739 for OpenCL and 263,779 for Vulkan. The GPU sits at the 86th percentile when compared to all GPUs, with an average benchmark score of 54,247. Its nearest rivals include the NVIDIA GeForce RTX 4080 SUPER at 54,209 (delta of +0.1%), the AMD Radeon Pro W5700X at 54,828 (delta of -1.1%), and the AMD Radeon RX 6750 GRE 12 GB at 55,698 (delta of -2.6%).

Given the RTX 4080's massive compute power, Roblox at 1080p is clearly not stressing the GPU. The measured data shows that at 1080p Low, the average FPS is 554, while at 1080p Ultra, it drops to 420 FPS. This 134 FPS drop when moving from Low to Ultra is more indicative of CPU-side limitations than GPU-side ones, as the GPU has plenty of headroom to render simple Roblox scenes. The GPU's role becomes more apparent at 4K, where the Ultra setting yields 158 FPS, and the Low setting yields 243 FPS. The gap between Low and Ultra at 4K is 85 FPS, which is smaller than the 134 FPS gap at 1080p, suggesting that at higher resolutions, the GPU starts to take on more of the load, but it is still not the primary limiting factor given the high absolute frame rates.

The RTX 4080's 16 GB of VRAM is far more than Roblox requires, even at 4K Ultra, so memory capacity is not a concern in this title. The GPU's 716.8 GB/s bandwidth and 48.74 TFLOPS are overkill for a game that is primarily CPU-bound at lower resolutions. This creates an interesting dynamic where the GPU is underutilized at 1080p, as evidenced by the fact that the FPS at 1080p Low (554) is only slightly higher than at 1080p High (514), a difference of just 40 FPS, while the difference between 1080p High and 1080p Ultra is 94 FPS, indicating that the Ultra preset introduces CPU-intensive effects that limit performance.

Settings Recommendations

Based on the measured FPS rows, the data indicates that the Medium preset offers the best balance between visual quality and performance for this combo, particularly at lower resolutions. At 1080p, the Medium preset averages 536 FPS, which is only 18 FPS lower than the Low preset's 554 FPS, while providing significantly better visual fidelity. The High preset at 1080p drops to 514 FPS, and the Ultra preset falls to 420 FPS. The Medium preset's minimum FPS at 1080p is 456, which is still well above the refresh rate of most high-end monitors, ensuring smooth gameplay even in demanding scenes.

At 1440p, the Medium preset averages 390 FPS, with a minimum of 332 FPS and a maximum of 449 FPS. This is a substantial drop from the 1080p Medium average of 536 FPS, representing a 146 FPS decrease, but the absolute numbers remain very high. The Low preset at 1440p achieves 429 FPS, while the High preset achieves 345 FPS, and the Ultra preset drops to 280 FPS. For players with 144Hz or 165Hz monitors, the Medium preset at 1440p is more than sufficient, and even the Ultra preset at 280 FPS exceeds the refresh rate of most displays.

At 4K, the Medium preset averages 221 FPS, with a minimum of 188 FPS and a maximum of 254 FPS. This is the only resolution where the Medium preset's minimum FPS falls below 200, but it is still comfortably above 144Hz. The Low preset at 4K averages 243 FPS, while the High preset averages 195 FPS, and the Ultra preset drops to 158 FPS. The data suggests that at 4K, the Medium preset is the sweet spot, as it provides a 66 FPS advantage over Ultra while looking noticeably better than Low. The Ultra preset at 4K, while still playable at 158 FPS, represents a 63 FPS drop from Medium, which is a significant performance penalty for incremental visual gains in a game like Roblox.

How This Combo Ranks

The combination of the Intel Core i5-9400 and NVIDIA GeForce RTX 4080 ranks 372nd out of 3,711 tested combos in Roblox. This places the combo in the top 10% of all tested configurations, which is a strong result for a processor that is several generations old paired with a flagship-class GPU. The rank is notable because the CPU is clearly the weaker link in this pairing, as evidenced by its 47th percentile ranking among all CPUs, while the GPU sits at the 86th percentile. Despite this imbalance, the combo still performs exceptionally well in Roblox due to the game's relatively low system requirements.

The combo's rank of 372 out of 3,711 means that roughly 3,339 other combos perform worse in this game, while only 371 perform better. Given that the RTX 4080 is among the most powerful consumer GPUs available, the combos that outperform this one likely feature more modern CPUs with higher single-threaded performance. The i5-9400's single-core score of 935 in Cinebench R23 is modest by today's standards, and in a game like Roblox that relies heavily on single-thread performance, this is the primary factor holding the combo back from a higher rank. However, the data shows that even with this CPU limitation, the combo delivers frame rates that are far in excess of what most displays can show, making the rank more of a theoretical measure than a practical limitation.

The delta between this combo's CPU and GPU performance is stark: the CPU's average benchmark score of 2,254 is only 4.2% of the GPU's average benchmark score of 54,247. This suggests that the system is heavily GPU-saturated from a hardware perspective, but in Roblox specifically, the CPU becomes the bottleneck at lower resolutions. The combo's rank reflects this dynamic, as it performs better at higher resolutions where the GPU takes on more of the work, but the absolute frame rates at all resolutions are high enough that the rank difference is unlikely to be noticeable to the end user.

Resolution Scaling

The measured FPS data shows a clear pattern of performance degradation as resolution increases from 1080p to 4K, with the magnitude of the drop varying by settings preset. At Low settings, the average FPS goes from 554 at 1080p to 429 at 1440p (a 125 FPS drop) and then to 243 at 4K (a further 186 FPS drop from 1440p). This represents a 56% reduction in FPS from 1080p to 4K at Low settings, which is a significant decrease but still leaves the combo at a very playable 243 FPS at 4K.

At Medium settings, the FPS drops from 536 at 1080p to 390 at 1440p (a 146 FPS drop) and then to 221 at 4K (a 169 FPS drop from 1440p). The total reduction from 1080p to 4K at Medium is 315 FPS, or 59%. At High settings, the FPS goes from 514 at 1080p to 345 at 1440p (a 169 FPS drop) and then to 195 at 4K (a 150 FPS drop from 1440p), for a total reduction of 319 FPS, or 62%. At Ultra settings, the FPS drops from 420 at 1080p to 280 at 1440p (a 140 FPS drop) and then to 158 at 4K (a 122 FPS drop from 1440p), for a total reduction of 262 FPS, or 62%.

The pattern of FPS drops from 1080p to 1440p is consistently around 125-169 FPS across all settings, while the drops from 1440p to 4K are slightly smaller, ranging from 122-186 FPS. This suggests that the scaling from 1080p to 1440p is somewhat steeper relative to the baseline FPS, while the 1440p to 4K scaling is more consistent in absolute terms. The fact that the FPS remains above 150 even at 4K Ultra indicates that the GPU is not the limiting factor in this game, as the RTX 4080 has more than enough power to render Roblox at any resolution. Instead, the CPU's single-threaded performance limits the frame rate at lower resolutions, where the GPU is waiting for the CPU to submit draw calls.

Measured FPS Breakdown

The measured FPS data provides a comprehensive picture of how this combo performs across three resolutions and four settings presets. At 1920x1080, the Low preset delivers an average of 554 FPS, the Medium preset delivers 536 FPS with a minimum of 456 and a maximum of 617, the High preset delivers 514 FPS, and the Ultra preset delivers 420 FPS. The difference between the Low and Ultra presets at 1080p is 134 FPS, which is the largest absolute gap across all resolutions, indicating that the Ultra preset imposes significant CPU overhead.

At 2560x1440, the Low preset averages 429 FPS, the Medium preset averages 390 FPS with a minimum of 332 and a maximum of 449, the High preset averages 345 FPS, and the Ultra preset averages 280 FPS. The gap between Low and Ultra at 1440p is 149 FPS, which is slightly larger than at 1080p, but the absolute values are lower. The Medium preset's minimum of 332 FPS at 1440p is still well above the refresh rate of any mainstream gaming monitor, making it a highly viable option for competitive play.

At 3840x2160, the Low preset averages 243 FPS, the Medium preset averages 221 FPS with a minimum of 188 and a maximum of 254, the High preset averages 195 FPS, and the Ultra preset averages 158 FPS. The gap between Low and Ultra at 4K is 85 FPS, which is the smallest absolute gap across all resolutions, suggesting that the GPU is beginning to take on more of the workload at this resolution. However, even the Ultra preset at 4K delivers 158 FPS, which exceeds the refresh rate of most high-end 4K displays, making this combo more than adequate for Roblox at any setting.

The data also shows that the Medium preset consistently provides the most stable frame times, as it is the only preset with measured minimum and maximum FPS values. At 1080p Medium, the minimum is 456 FPS and the maximum is 617 FPS, representing a range of 161 FPS. At 1440p Medium, the minimum is 332 FPS and the maximum is 449 FPS, a range of 117 FPS. At 4K Medium, the minimum is 188 FPS and the maximum is 254 FPS, a range of 66 FPS. This decreasing range as resolution increases suggests that the frame time variance is more pronounced at lower resolutions, likely due to CPU-side fluctuations, while at 4K, the GPU's consistent rendering pipeline smooths out the frame delivery.