CPU_VS_GPU / 2026-09-11
Intel Core i7-8700KvsAMD RX 7900 XT
Complete bottleneck analysis at 1080p, 1440p, Ultrawide (UWQHD/SUWQHD), and 4K with estimated FPS for popular games.
16%
ESTIMATED CPU BOTTLENECK
Your CPU (Core i7-8700K) partially limits the RX 7900 XT at 2560x1440. In CPU-heavy scenes you will lose frames. Consider a CPU upgrade or a higher target resolution.
Load estimated by the model, not measured on your PC.
- PROCESSORIntel Core i7-8700K
- GRAPHICSAMD RX 7900 XT
- MEMORY16GB DDR4/DDR5
- RESOLUTION2560x1440
Average across the demanding titles at 2560x1440.
Average across the competitive titles, where the processor leads.
What the build draws (560 W) plus headroom.
DEEP-DIVE ANALYSIS
GENERATED BY THE ENGINEPairing the Intel Core i7-8700K (54/100 on our gaming index) with the AMD RX 7900 XT (56/100) 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.
Straight answer: aim for 1440p
At 1080p the Core i7-8700K becomes the limiting part (~41% CPU bottleneck), whereas at 4K the RX 7900 XT is the limiting part (~17% GPU bottleneck). We put the target at 1440p: the highest of the usual 16:9 sizes where AAA titles still return 79 FPS, which is above 60. The table below breaks out all twelve resolutions on their own, ultrawide formats included.
Think of resolution as a dial that splits the weight between CPU and GPU. Drop to 1080p and you wring out the RX 7900 XT while leaning harder on the Core i7-8700K; push to 4K and the opposite happens. Synergy here swings between 83% and 59% depending on where you sit.
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 ~32 FPS at 4K, which is where the RX 7900 XT's ceiling really shows. Overall, expect about 90 FPS average in AAA games at 1080p and around 53 FPS at 4K.
[CPU] Core i7-8700K
The Core i7-8700K scores 54/100 on this model's gaming scale, with 6 cores and 12 threads. In this pairing its job is to serve frames fast enough to never leave the graphics card waiting.
[GPU] RX 7900 XT
On the graphics side, the RX 7900 XT rates 56/100 for gaming in this model. Its 20 GB of GDDR6 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 5 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 AMD GPU — a perfectly valid mix that imposes no penalty.
WHAT TO CHANGE, AND WHAT IT COSTS
At 1440p the Core i7-8700K sets the frame rate and leaves part of the RX 7900 XT idle. 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 7 5700X: about 22% 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 i7-8700K
- Cores6C / 12T
- Clock3.7 – 4.7 GHz
- TDP95 W
- SocketLGA1151
- Single-thread2,714
- Multi-thread13,561
- L3 cache12 MB
[GPU] AMD RX 7900 XT
- VRAM20 GB GDDR6
- Memory bus320-bit
- TDP315 W
- G3D Mark34,519
- Memory bandwidth800 GB/s
BOTTLENECK BY RESOLUTION
SYNERGY · AVERAGE FPSYour CPU (Core i7-8700K) cannot feed the RX 7900 XT 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 i7-8700K) partially limits the RX 7900 XT at 2560x1440. In CPU-heavy scenes you will lose frames. Consider a CPU upgrade or a higher target resolution.
Your CPU (Core i7-8700K) and GPU (RX 7900 XT) are an exceptionally balanced match for gaming at 3440x1440 (Ultrawide 21:9). No realistic component swap would meaningfully improve this build.
Your GPU (RX 7900 XT) is a slight limiting factor at 5120x1440 (Super Ultrawide 32:9), with limited real-world impact. Most titles will run smoothly.
Your GPU (RX 7900 XT) 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 i7-8700K (95W) and RX 7900 XT (315W) add up to roughly 410W under load. Adding 150W for the rest of the system gives 560W, and with a 30% transient margin, 750W is the safe figure.
VIDEO MEMORY AND PCIe
The RX 7900 XT's memory bus (320-bit) and bandwidth (800 GB/s) describe its own video memory, meaning how fast the card reads its 20 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 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 AMD RX 7900 XT?
At 1080p the Core i7-8700K becomes the limiting part (~41% CPU bottleneck), whereas at 4K the RX 7900 XT is the limiting part (~17% GPU bottleneck). Overall, the GPU is the limit at high resolution, with 75% average efficiency across the 12 resolutions our model tests. The resolution we would target with this pair is 1440p, where AAA games average 79 FPS.
How many FPS do the Core i7-8700K and RX 7900 XT get at 1080p?
At 1080p this combination averages about 90 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 53 FPS on average in AAA titles at 4K, with the RX 7900 XT 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 RX 7900 XT?
With an estimated combined draw of 410W across CPU and GPU, we recommend at least a 750W 80+ Gold supply (ideally ATX 3.0) to run with headroom.
Is the RX 7900 XT's 20 GB of VRAM enough?
In the model, 20 GB covers all 11 games it tracks even at 4K with high textures, so video memory is not the constraint for this pairing.