CPU_VS_GPU / 2026-09-11
Intel Core i5-9400FvsNVIDIA RTX 5090
Complete bottleneck analysis at 1080p, 1440p, Ultrawide (UWQHD/SUWQHD), and 4K with estimated FPS for popular games.
56%
ESTIMATED CPU BOTTLENECK
Your CPU (Core i5-9400F) cannot feed the RTX 5090 fast enough at 2560x1440. The GPU sits waiting for frames, causing stutter and noticeable drops. A CPU upgrade is the highest-impact change you can make.
Load estimated by the model, not measured on your PC.
- PROCESSORIntel Core i5-9400F
- GRAPHICSNVIDIA RTX 5090
- MEMORY16GB DDR4/DDR5
- RESOLUTION2560x1440
Average across the demanding titles at 2560x1440.
Average across the competitive titles, where the processor leads.
What the build draws (790 W) plus headroom.
DEEP-DIVE ANALYSIS
GENERATED BY THE ENGINEPairing the Intel Core i5-9400F (46/100 on our gaming index) with the NVIDIA RTX 5090 (96/100) raises one practical question: do they pull together, or does one hold the other back? We ran this exact combination across all supported resolutions to answer it with numbers rather than guesswork.
Quick take: 5K is the resolution to target
The Core i5-9400F sets the limit at both ends of the range, though it loosens as resolution climbs: ~61% CPU bottleneck at 1080p against ~39% at 4K. We put the target at 5K: the highest of the usual 16:9 sizes where AAA titles still return 62 FPS, which is above 60. The table below breaks out all twelve resolutions on their own, ultrawide formats included.
As you climb from 1080p to 4K, the load shifts from the processor toward the graphics card: every extra pixel lands on the RTX 5090. Here, efficiency moves from 39% at 1080p to 61% at 4K — which shows the part the frame rate depends on at each end.
Down to real numbers: In esports titles like Valorant this pair flies — around 275 FPS at 1080p, plenty for a high-refresh monitor. At the other end, a demanding AAA like Elden Ring drops to ~52 FPS at 4K, which is where the RTX 5090's ceiling really shows. Overall, expect about 66 FPS average in AAA games at 1080p and around 66 FPS at 4K.
[CPU] Core i5-9400F
On the CPU side: the Core i5-9400F rates 46/100 for gaming in this model and brings 6 cores and 6 threads. At lower resolutions it's the one setting the pace for the whole system.
[GPU] RTX 5090
On the graphics side, the RTX 5090 rates 96/100 for gaming in this model. Its 32 GB of GDDR7 set how far it can go on resolution and texture quality before video memory runs short. The higher the resolution, the more of the frame rate depends on it.
A detail that's easy to overlook: The graphics card is about 6 years newer than the processor, so watch that the Core i5-9400F doesn't fall short in the most CPU-dependent games. You're combining an Intel platform with an NVIDIA GPU — a perfectly valid mix that imposes no penalty.
WHAT TO CHANGE, AND WHAT IT COSTS
At 1440p the Core i5-9400F sets the frame rate and leaves part of the RTX 5090 idle. The cheapest processor in our catalogue that keeps the card fully fed and clears our bar (at least 10% more frames) is the Intel Core i9-14900KS: about 188% more in this model, with this card and 16 GB. It uses a different socket (LGA1700 instead of LGA1151), so the cost includes a motherboard.
The gain is the model's estimate at 2560x1440 with 16 GB, not a measurement of your PC, and prices change: check them at the retailer before deciding.
PRICE OF THIS PAGE'S PAIRING
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SPECIFICATIONS
CATALOGUE DATA[CPU] Intel Core i5-9400F
- Cores6C / 6T
- Clock2.9 – 4.1 GHz
- TDP65 W
- SocketLGA1151
- Single-thread2,421
- Multi-thread9,457
- L3 cache9 MB
[GPU] NVIDIA RTX 5090
- VRAM32 GB GDDR7
- Memory bus512-bit
- TDP575 W
- G3D Mark57,120
- Memory bandwidth1792 GB/s
BOTTLENECK BY RESOLUTION
SYNERGY · AVERAGE FPSYour CPU (Core i5-9400F) cannot feed the RTX 5090 fast enough at 1920x1080. The GPU sits waiting for frames, causing stutter and noticeable drops. A CPU upgrade is the highest-impact change you can make.
Your CPU (Core i5-9400F) cannot feed the RTX 5090 fast enough at 2560x1440. The GPU sits waiting for frames, causing stutter and noticeable drops. A CPU upgrade is the highest-impact change you can make.
Your CPU (Core i5-9400F) cannot feed the RTX 5090 fast enough at 3440x1440 (Ultrawide 21:9). The GPU sits waiting for frames, causing stutter and noticeable drops. A CPU upgrade is the highest-impact change you can make.
Your CPU (Core i5-9400F) cannot feed the RTX 5090 fast enough at 5120x1440 (Super Ultrawide 32:9). The GPU sits waiting for frames, causing stutter and noticeable drops. A CPU upgrade is the highest-impact change you can make.
Your CPU (Core i5-9400F) cannot feed the RTX 5090 fast enough at 4K. The GPU sits waiting for frames, causing stutter and noticeable drops. A CPU upgrade is the highest-impact change you can make.
ESTIMATED FPS BY GAME
1920x1080SYSTEM DIAGNOSTICS
POWER · VRAM & PCIe · RAMPOWER ESTIMATION
The Core i5-9400F (65W) and RTX 5090 (575W) add up to roughly 640W under load. Adding 150W for the rest of the system gives 790W, and with a 30% transient margin, 1050W is the safe figure.
VIDEO MEMORY AND PCIe
The RTX 5090's memory bus (512-bit) and bandwidth (1792 GB/s) describe its own video memory, meaning how fast the card reads its 32 GB of GDDR7, not the PCIe link to the processor. The PCIe link depends on the card, the processor and the motherboard slot together; our catalogue does not record PCIe generation or lane count, so the model does not estimate it. It matters most for cards with an eight-lane interface in older PCIe 3.0 boards: check the card's and the board's specifications.
SYSTEM MEMORY
This page assumes 16 GB in dual channel. At 5K, the resolution recommended above, that meets the model's capacity target of 16 GB (enough for three in four of the games it covers), so more capacity would add little or nothing there. The target stays at 16 GB even at 4K, so a larger kit is for heavy multitasking or mods, not for these games. Memory speed and a second channel act on the processor's ceiling instead: they matter in the games the CPU limits, by an amount that depends on the game, and the calculator lets you enter your own kit.
HOW THIS PAGE IS CALCULATED
ENGINE v2026.08 · 2026-09-11CALCULATED, NOT WRITTEN
Every figure and every sentence comes from the same deterministic engine, driven by the catalogue specifications. That is what makes it reproducible: with the same engine version (2026.08) and the same catalogue, the same pairing always gives the same result. When either changes, the version and date above change with it, and the changelog says why.
WHERE THE DATA COMES FROM
Specifications come from the official AMD, Intel and NVIDIA datasheets together with PassMark and TechPowerUp. The gaming indices are calibrated against frame rates published by review outlets (TechPowerUp, TechSpot / Hardware Unboxed, Tom's Hardware, Gamers Nexus, Digital Foundry) rather than synthetic scores. That data is compiled, not measured here: this site runs no test bench of its own.
STATED LIMITS
Figures estimate native raster performance at high/ultra quality, with no ray tracing, upscaling or frame generation. We do not yet publish an externally validated error margin — the accuracy page states exactly where that stands.
* Affiliate disclosure: the Amazon links exist to show pricing. As an Amazon Associate we earn from qualifying purchases at no extra cost to you. Recommendation order is decided by the engine and does not depend on commission.
TRY WITH YOUR OWN HARDWARE
Customize RAM, resolution, and discover upgrade recommendations.
FREQUENTLY ASKED QUESTIONS
5Does the Intel Core i5-9400F bottleneck the NVIDIA RTX 5090?
The Core i5-9400F sets the limit at both ends of the range, though it loosens as resolution climbs: ~61% CPU bottleneck at 1080p against ~39% at 4K. Overall, there is some mismatch depending on resolution, with 57% average efficiency across the 12 resolutions our model tests. The resolution we would target with this pair is 5K, where AAA games average 62 FPS.
How many FPS do the Core i5-9400F and RTX 5090 get at 1080p?
At 1080p this combination averages about 66 FPS in AAA games and around 172 FPS in esports titles. In Valorant we estimate up to 275 FPS.
Is this pairing good for 4K gaming?
Yes. At 4K this pairing averages about 66 FPS in AAA titles, at or above the 60 FPS we treat as smooth.
What power supply do I need for the Core i5-9400F and RTX 5090?
With an estimated combined draw of 640W across CPU and GPU, we recommend at least a 1050W 80+ Gold supply (ideally ATX 3.0) to run with headroom.
Is the RTX 5090's 32 GB of VRAM enough?
In the model, 32 GB covers all 11 games it tracks even at 4K with high textures, so video memory is not the constraint for this pairing.