Doom

# Doom — Intel Core i5-9400 + AMD Radeon RX 7900 XT

The pairing of a six-core Intel Core i5-9400 with the Radeon RX 7900 XT delivers a curious mix of raw GPU horsepower and aging CPU architecture in Doom. The benchmark data reveals a system that is overwhelmingly GPU-bound at higher resolutions, yet begins to show CPU limitations at 1080p, where the game's famously efficient id Tech engine lets the processor's weaknesses surface. The RX 7900 XT, with its 20 GB of GDDR6 memory and 800.0 GB/s bandwidth, is clearly the dominant component, but the i5-9400's modest 2.90 GHz base and 4.10 GHz boost clocks create an interesting bottleneck dynamic that shifts depending on resolution and settings.

Resolution Scaling

The FPS drop from 1080p to 4K tells a textbook story of GPU-bound scaling, but with a twist. At High settings, the system delivers 230.1 FPS at 1920x1080, falls to 158.7 FPS at 2560x1440, and bottoms out at 87.9 FPS at 3840x2160. That represents a 31% reduction from 1080p to 1440p, and a further 45% drop from 1440p to 4K. The total scaling from 1080p to 4K is a 62% reduction, which is substantial but not catastrophic — indicating the GPU is still managing the load well even at 4K.

However, the Low settings row reveals the CPU's influence more clearly. At 1080p Low, the system hits 253.8 FPS, but moving to 1440p Low only reduces this to 221.7 FPS — a mere 13% decline. This shallow scaling suggests that at 1080p Low, the i5-9400 is becoming the limiting factor, preventing the RX 7900 XT from stretching its legs. The 4K Low figure of 117.3 FPS then shows a 47% drop from 1440p, indicating the GPU reasserts its dominance at the highest resolution. The pattern is consistent: the less demanding the settings, the earlier the CPU bottleneck appears.

FAQ

Q: What is the highest average FPS this combo achieves in Doom?

A: The peak measured average is 253.8 FPS at 1920x1080 with Low settings. At the opposite extreme, Ultra settings at 3840x2160 yields 71 FPS.

Q: How does the RX 7900 XT's memory configuration affect Doom performance?

A: The GPU's 20 GB of GDDR6 memory on a 320-bit bus provides 800.0 GB/s of bandwidth. This is far more than Doom requires, even at 4K Ultra, so memory bandwidth is not a limiting factor in any measured configuration.

Q: Is the Core i5-9400 holding back the RX 7900 XT at 1080p?

A: Evidence suggests yes. At 1080p, the difference between Low (253.8 FPS) and High (230.1 FPS) is only 10%, while at 1440p the same settings gap is 28% (221.7 vs 158.7 FPS). The compressed spread at 1080p indicates CPU limitation.

Q: What is this combo's rank among all tested combinations?

A: The combo ranks 416 out of 1681 tested combinations in Doom, placing it in the upper quartile of all systems tested.

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

A: The i5-9400 has an average benchmark score of 2305, which is 0.2% ahead of the Intel Core i3-10305 (2300) and 0.2% ahead of the Intel Core i3-1125G4 (2299). It trails the Intel Core i7-8809G (2319) by 0.6%.

Q: Does the RX 7900 XT's Ultra preset deliver playable 4K performance?

A: Yes, with 71 FPS at 3840x2160 Ultra, the combo remains above the 60 FPS threshold, though it is the only 4K preset tested that dips below 87.9 FPS.

GPU Role

The Radeon RX 7900 XT is an absolute powerhouse in this pairing, and the Doom results reflect its capabilities across the board. Its 5376 shading units, 336 texture mapping units, and 192 raster output pipelines provide the raw compute necessary for high-refresh-rate gaming. The boost clock of 2394 MHz, with a game clock of 2025 MHz, keeps the GPU well-fed even under sustained load. The 20 GB frame buffer is excessive for a 2016 title, but it ensures zero memory pressure regardless of resolution or settings.

The GPU's benchmark profile reinforces its strength. With a Passmark G3D score of 29009 and an average benchmark score of 38358, the RX 7900 XT sits at the 82nd percentile of all GPUs. Its nearest rivals in the database are the NVIDIA GeForce RTX 5080 Mobile (38349, 0% delta) and the NVIDIA CMP 70HX (38225, 0.3% ahead), which places it in elite company. In Doom specifically, the GPU's ability to maintain 87.9 FPS at 4K High and 71 FPS at 4K Ultra demonstrates that even the most demanding presets are within reach.

The interplay between the GPU's 800.0 GB/s memory bandwidth and Doom's engine is worth noting. The game's heavy use of texture streaming benefits directly from this bandwidth, which explains why the drop from Medium (105.3 FPS) to Ultra (71 FPS) at 4K is steep but not crippling — the memory subsystem never becomes a bottleneck, allowing the GPU's compute units to do the heavy lifting.

Measured FPS Breakdown

At 1920x1080, the combo delivers 253.8 FPS on Low, 244.9 FPS on Medium, 230.1 FPS on High, and 205.6 FPS on Ultra. The spread from Low to Ultra is 48.2 FPS, or 19%. This is the tightest range across all resolutions, reinforcing the CPU-bound nature of 1080p gameplay.

Moving to 2560x1440, the numbers shift dramatically: 221.7 FPS on Low, 192.2 FPS on Medium, 158.7 FPS on High, and 130.2 FPS on Ultra. The Low-to-Ultra gap expands to 91.5 FPS, or 41%, showing the GPU taking over as the primary performance driver. The 1440p figures are particularly strong — even Ultra stays well above 120 FPS, making this resolution the sweet spot for high-refresh displays.

At 3840x2160, the GPU's limits become apparent: 117.3 FPS on Low, 105.3 FPS on Medium, 87.9 FPS on High, and 71 FPS on Ultra. The Ultra preset at 4K is the only configuration that dips below 87.9 FPS, but the fact that it remains playable at 71 FPS is impressive for a six-core CPU from 2018 paired with a 2022 flagship GPU. The scaling from Low to Ultra at 4K is a 39% drop, which is moderate and indicates the GPU is the clear limiting factor at this resolution.

Settings Recommendations

For players prioritizing maximum frame rates, the 1080p Low preset at 253.8 FPS is the clear choice, though the CPU bottleneck means the jump to Medium (244.9 FPS) costs less than 4% performance while likely improving visual quality significantly. At 1440p, the Medium preset (192.2 FPS) offers the best balance — it stays above 190 FPS while providing a substantial upgrade over Low (221.7 FPS). The High preset at 1440p (158.7 FPS) is also excellent for 144Hz monitors, offering a 22% reduction from Medium in exchange for better fidelity.

At 4K, the choice depends on the display's refresh rate. The High preset at 87.9 FPS is ideal for 90Hz or 120Hz panels with adaptive sync, while the Ultra preset at 71 FPS is only recommended for 60Hz displays where maximum visual quality is paramount. The Medium preset at 105.3 FPS is arguably the best 4K option, providing a 20% boost over High while remaining visually rich. Across all resolutions, the data suggests skipping Ultra unless visual fidelity is the absolute priority — the performance cost of 20-30% over High rarely justifies the marginal image quality gain in a fast-paced FPS.

CPU Role

The Intel Core i5-9400 is a six-core, six-thread processor from the Coffee Lake Refresh generation, built on Intel's 14 nm process. Its 2.90 GHz base clock and 4.10 GHz boost clock, combined with 9 MB of shared L3 cache, provide adequate single-thread performance for most games. However, its 65 W TDP and lack of hyper-threading mean it can struggle in CPU-bound scenarios, and Doom at 1080p Low reveals this limitation clearly.

The CPU's benchmark scores paint a picture of a mid-range part. A Cinebench R23 multicore score of 7969 and single-core score of 1125 place it at the 50th percentile of all CPUs. Its average benchmark score of 2305 is nearly identical to the Intel Core i3-10305 (2300, 0.2% ahead) and the Intel Core i3-1125G4 (2299, 0.2% ahead), while trailing the Intel Core i7-8809G (2319) by 0.6%. This tight grouping around the 2300 mark indicates the i5-9400 is firmly in the mid-range tier, neither a bottleneck nor a performer in most scenarios.

In Doom specifically, the CPU's influence is most visible in the 1080p results. The 205.6 FPS at Ultra and 253.8 FPS at Low represent a 48 FPS spread, but the fact that even the lowest settings cannot push past 253.8 FPS suggests the processor is capping performance. At 1440p and 4K, the GPU becomes the limiting factor, and the CPU's role diminishes — the data shows this shift clearly, with the 1440p Low-to-Ultra spread expanding to 91.5 FPS.

How This Combo Ranks

The combo ranks 416 out of 1681 tested combinations in Doom, placing it in the top 25% of all systems. This is a strong result, but it raises an interesting question: why isn't this pairing ranked higher given the GPU's elite status? The answer lies in the CPU's percentile ranking of 50, which drags down the overall combo score despite the GPU's 82nd percentile standing.

The rank of 416 suggests that while the RX 7900 XT delivers exceptional raw performance, the i5-9400 prevents the system from reaching the top echelons of the rankings. In a game like Doom, where CPU overhead is relatively low, this pairing still manages to deliver excellent frame rates across all resolutions and settings. However, the data implies that pairing the RX 7900 XT with a more powerful CPU would yield even higher rankings, as the GPU has headroom at 1080p that the current processor cannot exploit.

Overall, the 416th rank out of 1681 reflects the RX 7900 XT's dominance, but it also highlights the i5-9400 as the weak link in an otherwise formidable gaming system. For owners of this combo, the practical takeaway is clear: prioritize higher resolutions and settings to shift the workload onto the GPU, where the system's strengths lie.