CPU_VS_GPU / 2026-09-11
Intel Core i5-9400FvsAMD RX 6800
Complete bottleneck analysis at 1080p, 1440p, Ultrawide (UWQHD/SUWQHD), and 4K with estimated FPS for popular games.
12%
ESTIMATED CPU BOTTLENECK
Your CPU (Core i5-9400F) introduces a slight limitation at 2560x1440. Real-world impact is small and both components work well together.
Below 15% this is a normal imbalance: nothing needs changing to play well.
Load estimated by the model, not measured on your PC.
- PROCESSORIntel Core i5-9400F
- GRAPHICSAMD RX 6800
- MEMORY16GB DDR4/DDR5
- RESOLUTION2560x1440
Average across the demanding titles at 2560x1440.
Average across the competitive titles, where the processor leads.
What the build draws (465 W) plus headroom.
DEEP-DIVE ANALYSIS
GENERATED BY THE ENGINEAre the Intel Core i5-9400F and the AMD RX 6800 a good match? To find out we modelled the pair from 1080p up to 4K, cross-referencing the model's gaming scores for the CPU (46/100) and the GPU (34/100), calibrated against measured benchmarks rather than synthetic scores, with the demand profile of each game.
Verdict: play this build at 1080p
At 1080p the Core i5-9400F becomes the limiting part (~38% CPU bottleneck), whereas at 4K the RX 6800 is the limiting part (~26% GPU bottleneck). Of the common 16:9 sizes, the highest this pair holds above 60 FPS in AAA titles is 1080p, where it averages 63 FPS — that is the resolution worth buying a monitor for. Across every resolution tested, ultrawides included, the system runs at 70% average efficiency.
Think of resolution as a dial that splits the weight between CPU and GPU. Drop to 1080p and you wring out the RX 6800 while leaning harder on the Core i5-9400F; push to 4K and the opposite happens. Synergy here swings between 74% and 62% depending on where you sit.
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 ~18 FPS at 4K, which is where the RX 6800's ceiling really shows. Overall, expect about 63 FPS average in AAA games at 1080p and around 34 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] RX 6800
The RX 6800 scores 34/100 on this model's gaming scale. Its 16 GB of GDDR6 set how far it can go on resolution and texture quality before video memory runs short. It draws every pixel, so its weight grows the higher you push the resolution.
Beyond the FPS: 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.
WHAT TO CHANGE, AND WHAT IT COSTS
At 1440p the Core i5-9400F sets the frame rate and leaves part of the RX 6800 idle. The imbalance is small (12%), so this is optional rather than a fix. The cheapest processor in our catalogue that keeps the card fully fed and clears our bar (at least 10% more frames) is the AMD Ryzen 5 5600: about 35% more in this model, with this card and 16 GB. It uses a different socket (AM4 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] AMD RX 6800
- VRAM16 GB GDDR6
- Memory bus256-bit
- TDP250 W
- G3D Mark22,070
- Memory bandwidth512 GB/s
BOTTLENECK BY RESOLUTION
SYNERGY · AVERAGE FPSYour CPU (Core i5-9400F) cannot feed the RX 6800 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) introduces a slight limitation at 2560x1440. Real-world impact is small and both components work well together.
Your CPU (Core i5-9400F) and GPU (RX 6800) are an exceptionally balanced match for gaming at 3440x1440 (Ultrawide 21:9). No realistic component swap would meaningfully improve this build.
Your GPU (RX 6800) is the limiting factor at 5120x1440 (Super Ultrawide 32:9). In graphically demanding titles you will see lower frame rates; a faster GPU would deliver a clear improvement.
Your GPU (RX 6800) is the limiting factor at 4K. In graphically demanding titles you will see lower frame rates; a faster GPU would deliver a clear improvement.
ESTIMATED FPS BY GAME
1920x1080SYSTEM DIAGNOSTICS
POWER · VRAM & PCIe · RAMPOWER ESTIMATION
The Core i5-9400F (65W) and RX 6800 (250W) add up to roughly 315W under load. Adding 150W for the rest of the system gives 465W, and with a 30% transient margin, 650W is the safe figure.
VIDEO MEMORY AND PCIe
The RX 6800's memory bus (256-bit) and bandwidth (512 GB/s) describe its own video memory, meaning how fast the card reads its 16 GB of GDDR6, 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 6800?
At 1080p the Core i5-9400F becomes the limiting part (~38% CPU bottleneck), whereas at 4K the RX 6800 is the limiting part (~26% GPU bottleneck). Overall, the GPU is the limit at high resolution, with 70% average efficiency across the 12 resolutions our model tests. The resolution we would target with this pair is 1080p, where AAA games average 63 FPS.
How many FPS do the Core i5-9400F and RX 6800 get at 1080p?
At 1080p this combination averages about 63 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?
Playable rather than smooth: about 34 FPS on average in AAA titles at 4K, with the RX 6800 setting the limit. Upscaling (DLSS, FSR or XeSS) or lower settings are the usual way to reach 60 FPS.
What power supply do I need for the Core i5-9400F and RX 6800?
With an estimated combined draw of 315W across CPU and GPU, we recommend at least a 650W 80+ Gold supply (ideally ATX 3.0) to run with headroom.
Is the RX 6800's 16 GB of VRAM enough?
In the model, 16 GB covers all 11 games it tracks even at 4K with high textures, so video memory is not the constraint for this pairing.