CPU_VS_GPU / 2026-09-11
Intel Core i5-9400FvsAMD RX 580 8GB
Complete bottleneck analysis at 1080p, 1440p, Ultrawide (UWQHD/SUWQHD), and 4K with estimated FPS for popular games.
56%
ESTIMATED GPU BOTTLENECK
Your GPU (RX 580 8GB) severely limits the system at 2560x1440, leaving the Core i5-9400F heavily underused. A faster GPU would improve performance dramatically.
Load estimated by the model, not measured on your PC.
- PROCESSORIntel Core i5-9400F
- GRAPHICSAMD RX 580 8GB
- MEMORY16GB DDR4/DDR5
- RESOLUTION2560x1440
Average across the demanding titles at 2560x1440.
Average across the competitive titles, where the processor leads.
What the build draws (400 W) plus headroom.
DEEP-DIVE ANALYSIS
GENERATED BY THE ENGINEPairing the Intel Core i5-9400F (46/100 on our gaming index) with the AMD RX 580 8GB (9/100) 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.
Verdict: this pair struggles in AAA titles
The RX 580 8GB sets the limit at both ends of the range: a ~30% GPU bottleneck at 1080p that widens to ~79% at 4K. There is no resolution here we would recommend for modern AAA titles: even at 1080p the average sits at 26 FPS. For esports, at around 150 FPS, the pairing is more than enough; anything heavier needs lower settings, upscaling, or different hardware.
As you climb from 1080p to 4K, the load shifts from the processor toward the graphics card: every extra pixel lands on the RX 580 8GB. Here, efficiency moves from 70% at 1080p to 21% at 4K — which shows the part the frame rate depends on at each end.
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 Alan Wake 2 drops to ~4 FPS at 4K, which is where the RX 580 8GB's ceiling really shows. Overall, expect about 26 FPS average in AAA games at 1080p and around 9 FPS at 4K.
[CPU] Core i5-9400F
The Core i5-9400F scores 46/100 on this model's gaming scale, with 6 cores and 6 threads. In this pairing its job is to serve frames fast enough to never leave the graphics card waiting.
[GPU] RX 580 8GB
The RX 580 8GB (9/100 on the model's gaming scale) supplies the raster muscle of the build. Its 8 GB of GDDR5 set how far it can go on resolution and texture quality before video memory runs short.
On the chemistry of the pair: Both parts come from nearby generations, which usually means a natural pairing with no platform surprises. You're combining an Intel platform with an AMD GPU — a perfectly valid mix that imposes no penalty.
DO YOU NEED TO CHANGE ANYTHING?
At 1440p the RX 580 8GB sets the frame rate. No card in our catalogue clears the bar we use for a recommendation: at least 25% more frames while the Core i5-9400F still keeps it fully fed. The closest, the NVIDIA RTX 5090, adds about 155% in this model. So there is no card we would tell you to buy for this pairing.
PRICE OF EACH PART
Affiliate links — we earn a small commission at no cost to you. Full disclosure
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] AMD RX 580 8GB
- VRAM8 GB GDDR5
- Memory bus256-bit
- TDP185 W
- G3D Mark8,788
- Memory bandwidth256 GB/s
BOTTLENECK BY RESOLUTION
SYNERGY · AVERAGE FPSYour GPU (RX 580 8GB) severely limits the system at 1920x1080, leaving the Core i5-9400F heavily underused. A faster GPU would improve performance dramatically.
Your GPU (RX 580 8GB) severely limits the system at 2560x1440, leaving the Core i5-9400F heavily underused. A faster GPU would improve performance dramatically.
Your GPU (RX 580 8GB) severely limits the system at 3440x1440 (Ultrawide 21:9), leaving the Core i5-9400F heavily underused. A faster GPU would improve performance dramatically.
Your GPU (RX 580 8GB) severely limits the system at 5120x1440 (Super Ultrawide 32:9), leaving the Core i5-9400F heavily underused. A faster GPU would improve performance dramatically.
Your GPU (RX 580 8GB) severely limits the system at 4K, leaving the Core i5-9400F heavily underused. A faster GPU would improve performance dramatically.
ESTIMATED FPS BY GAME
1920x1080SYSTEM DIAGNOSTICS
POWER · VRAM & PCIe · RAMPOWER ESTIMATION
The Core i5-9400F (65W) and RX 580 8GB (185W) add up to roughly 250W under load. Adding 150W for the rest of the system gives 400W, and with a 30% transient margin, 550W is the safe figure.
VIDEO MEMORY AND PCIe
The RX 580 8GB's memory bus (256-bit) and bandwidth (256 GB/s) describe its own video memory, meaning how fast the card reads its 8 GB of GDDR5, 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 1080p, 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 AMD RX 580 8GB?
The RX 580 8GB sets the limit at both ends of the range: a ~30% GPU bottleneck at 1080p that widens to ~79% at 4K. Overall, the GPU is the limit at high resolution, with 38% average efficiency across the 12 resolutions our model tests. For AAA titles we would not target any resolution above 1080p: even there the average is 26 FPS.
How many FPS do the Core i5-9400F and RX 580 8GB get at 1080p?
At 1080p this combination averages about 26 FPS in AAA games and around 150 FPS in esports titles. In Valorant we estimate up to 275 FPS.
Is this pairing good for 4K gaming?
Not for AAA titles at native high settings: about 9 FPS on average at 4K. It would take upscaling, much lower settings or faster hardware.
What power supply do I need for the Core i5-9400F and RX 580 8GB?
With an estimated combined draw of 250W across CPU and GPU, we recommend at least a 550W 80+ Gold supply (ideally ATX 3.0) to run with headroom.
Is the RX 580 8GB's 8 GB of VRAM enough?
8 GB falls short at 1440p for 3 of the 11 games the model tracks, and for 6 at 4K. In those titles expect to lower texture settings, or to see frame-time spikes if you do not.