CPU_VS_GPU / 2026-09-11
Intel Core i7-8700KvsNVIDIA RTX 3090
Complete bottleneck analysis at 1080p, 1440p, Ultrawide (UWQHD/SUWQHD), and 4K with estimated FPS for popular games.
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PERFECTLY BALANCED BUILD
Your CPU (Core i7-8700K) and GPU (RTX 3090) are an exceptionally balanced match for gaming at 2560x1440. No realistic component swap would meaningfully improve this build.
Load estimated by the model, not measured on your PC.
- PROCESSORIntel Core i7-8700K
- GRAPHICSNVIDIA RTX 3090
- MEMORY16GB DDR4/DDR5
- RESOLUTION2560x1440
Average across the demanding titles at 2560x1440.
Average across the competitive titles, where the processor leads.
What the build draws (595 W) plus headroom.
DEEP-DIVE ANALYSIS
GENERATED BY THE ENGINEThe Intel Core i7-8700K and the NVIDIA RTX 3090 each bring their own character. Below you'll see whether the union is balanced or whether one component wastes the other, with estimated FPS, power draw and recommendations tailored to this specific pair.
Verdict: play this build at 1440p
At 1080p the Core i7-8700K becomes the limiting part (~29% CPU bottleneck), whereas at 4K the RTX 3090 is the limiting part (~32% GPU bottleneck). One number decides the purchase: 1440p is the most demanding of the standard 16:9 sizes that still sustains 64 FPS on average in AAA games, above the 60 FPS bar we treat as smooth. Step up a rung and the frame rate drops below that mark.
Resolution reshuffles the priorities. At 1080p the Core i7-8700K's single-thread speed calls the shots; at 4K it's the raw muscle of the RTX 3090 that matters. That shift shows up in the numbers: 71% efficiency at 1080p versus 68% at 4K.
Translated into actual games: In esports titles like Valorant this pair flies — around 365 FPS at 1080p, plenty for a high-refresh monitor. At the other end, a demanding AAA like Alan Wake 2 drops to ~23 FPS at 4K, which is where the RTX 3090's ceiling really shows. Overall, expect about 83 FPS average in AAA games at 1080p and around 43 FPS at 4K.
[CPU] Core i7-8700K
The Core i7-8700K (54/100 on the model's gaming scale) brings 6 cores and 12 threads and determines how many frames per second the system can prepare.
[GPU] RTX 3090
On the graphics side, the RTX 3090 rates 43/100 for gaming in this model. Its 24 GB of GDDR6X 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.
Beyond the FPS: The graphics card is about 3 years newer than the processor, so watch that the Core i7-8700K 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.
DO YOU NEED TO CHANGE ANYTHING?
At 1440p neither part appreciably holds the other back, so there is nothing you need to change. The Core i7-8700K and the RTX 3090 stand as they are; an 800W supply gives the build headroom.
PRICE OF EACH PART
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SPECIFICATIONS
CATALOGUE DATA[CPU] Intel Core i7-8700K
- Cores6C / 12T
- Clock3.7 – 4.7 GHz
- TDP95 W
- SocketLGA1151
- Single-thread2,714
- Multi-thread13,561
- L3 cache12 MB
[GPU] NVIDIA RTX 3090
- VRAM24 GB GDDR6X
- Memory bus384-bit
- TDP350 W
- G3D Mark26,914
- Memory bandwidth936.2 GB/s
BOTTLENECK BY RESOLUTION
SYNERGY · AVERAGE FPSYour CPU (Core i7-8700K) partially limits the RTX 3090 at 1920x1080. In CPU-heavy scenes you will lose frames. Consider a CPU upgrade or a higher target resolution.
Your CPU (Core i7-8700K) and GPU (RTX 3090) are an exceptionally balanced match for gaming at 2560x1440. No realistic component swap would meaningfully improve this build.
Your GPU (RTX 3090) is a slight limiting factor at 3440x1440 (Ultrawide 21:9), with limited real-world impact. Most titles will run smoothly.
Your GPU (RTX 3090) 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 (RTX 3090) severely limits the system at 4K, leaving the Core i7-8700K heavily underused. A faster GPU would improve performance dramatically.
ESTIMATED FPS BY GAME
1920x1080SYSTEM DIAGNOSTICS
POWER · VRAM & PCIe · RAMPOWER ESTIMATION
The Core i7-8700K (95W) and RTX 3090 (350W) add up to roughly 445W under load. Adding 150W for the rest of the system gives 595W, and with a 30% transient margin, 800W is the safe figure.
VIDEO MEMORY AND PCIe
The RTX 3090's memory bus (384-bit) and bandwidth (936.2 GB/s) describe its own video memory, meaning how fast the card reads its 24 GB of GDDR6X, 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 1440p, 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 i7-8700K bottleneck the NVIDIA RTX 3090?
At 1080p the Core i7-8700K becomes the limiting part (~29% CPU bottleneck), whereas at 4K the RTX 3090 is the limiting part (~32% GPU bottleneck). Overall, the GPU is the limit at high resolution, with 72% average efficiency across the 12 resolutions our model tests. The resolution we would target with this pair is 1440p, where AAA games average 64 FPS.
How many FPS do the Core i7-8700K and RTX 3090 get at 1080p?
At 1080p this combination averages about 83 FPS in AAA games and around 234 FPS in esports titles. In Valorant we estimate up to 365 FPS.
Is this pairing good for 4K gaming?
Playable rather than smooth: about 43 FPS on average in AAA titles at 4K, with the RTX 3090 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 i7-8700K and RTX 3090?
With an estimated combined draw of 445W across CPU and GPU, we recommend at least an 800W 80+ Gold supply (ideally ATX 3.0) to run with headroom.
Is the RTX 3090's 24 GB of VRAM enough?
In the model, 24 GB covers all 11 games it tracks even at 4K with high textures, so video memory is not the constraint for this pairing.