How to Actually Test If Your PC Has a Bottleneck

✍️ By Muhammad Hashir · Founder, NextGen Calculators

You’re mid-match in Warzone. Frame rate tanks. The game stutters like it’s buffering. You’ve already lowered every setting and your GPU temps look fine — but something is clearly choking your system.

The problem probably isn’t your hardware being bad. It’s that one component is working a lot harder than the other. That’s a bottleneck. And most guides telling you how to find it are either too vague or just push you toward a number without explaining what’s actually happening inside your system.

I’ve built and tested over a dozen gaming rigs across the last several years — budget setups with i5s and used GTX 1080s, high-end Ryzen 9 builds pushing 4K, mid-range systems that punched way above their weight class. Finding bottlenecks is something I’ve done more times than I can count, and the process is less complicated than people make it.

Here’s what actually works.

What Is a Bottleneck and Why Does It Matter?

A bottleneck happens when one component finishes its work and then waits on another to catch up. In gaming, you’ll almost always be dealing with either:

CPU bottleneck — your processor can’t feed frames to the GPU fast enough. The GPU sits idle or at low utilization while the CPU is buried at 90–100%.

GPU bottleneck — your graphics card is maxed out rendering frames but the CPU is barely working. This is actually the “good” kind — it means your GPU is being fully utilized, which is what you want in graphically demanding games.

The problem is that most people confuse these two, or assume high CPU usage alone means they need a new processor. That’s not always true.

How to Check What CPU You Have (Before You Test Anything)

This matters because a lot of bottleneck symptoms depend on how many cores your CPU has and what clock speeds it runs at.

If you’re not sure how to find your CPU, open Task Manager (Ctrl + Shift + Esc), click the Performance tab, and look at the CPU section. It’ll show your processor model right there at the top. You can also open CPU-Z for detailed info including cache size, core count, and real-time clock speeds. For how to check what CPU you have without installing anything, just hit Windows key + Pause/Break — it’s in the Basic System Information panel.

Write this down. You’ll need it when cross-referencing benchmark data.

The Right Way to Test: Monitor While You Game

This is where most guides get lazy. They say “use MSI Afterburner” and leave it there. You need to know what you’re actually looking at.

Step 1: Set up MSI Afterburner with Riva Tuner on-screen display

Install MSI Afterburner and enable the overlay to show GPU usage, GPU temp, CPU usage, CPU temp, and frame time. Add RAM usage too if you’re suspicious of memory issues.

Step 2: Run a demanding gaming session — not a 2-minute idle test

Load into GTA 5’s city streets, a crowded Warzone lobby, or a Cyberpunk 2077 scene with RT enabled. These are CPU-intensive enough to stress different parts of your system depending on resolution.

Step 3: Watch the numbers live

Normal GPU usage for gaming: 95–99% at your target resolution and settings. If you’re seeing 50–70% GPU usage and low FPS at the same time, that’s the signal that your CPU is the bottleneck.

Normal CPU usage while gaming: Varies a lot. A six-core processor might sit at 60–80% evenly spread. If you’re seeing one or two cores pinned at 100% while others are barely loaded, that’s a CPU bottleneck — particularly in older games like GTA 5 that historically favor single-core speed.

If GPU is at 99% and CPU is at 40–60%, you’ve found your ceiling — it’s the GPU, and that’s expected. Lowering your game settings will shift that ceiling, which is how you confirm it.

How to Know If Your CPU Is Actually Bad vs Just Bottlenecked

There’s a difference between a CPU causing a bottleneck because it’s paired with a GPU that outclasses it, and a CPU that’s genuinely degraded or running poorly.

Signs a CPU might be bad or in trouble:

• Frametime spikes with no consistency (wildly variable frame delivery)
• CPU runs at 100% usage even on your desktop or during lightweight tasks
• Games crash or freeze while CPU temps are normal
• Thermal throttling — your CPU drops clock speeds to protect itself from overheating

To check if thermal throttling is happening, open HWMonitor and watch your CPU’s clock speed under full load. If your i7 is rated for 4.9 GHz boost but you’re seeing it drop to 2.4 GHz during gaming, it’s thermal throttling. Your cooler isn’t keeping up, or thermal paste has dried out.

How long does bottlenecking run your system hot? Sustained 100% CPU usage generates serious heat — if your cooler can’t handle it, temperatures will climb within 5–10 minutes of heavy gaming. Chronic throttling over time isn’t just a performance issue; it’s genuinely harder on the silicon.

Valorant vs Cyberpunk: Why the Same PC Bottlenecks Differently

This is something I had to learn the hard way. A Ryzen 5 3600 paired with an RTX 3070 would GPU-bottleneck at 1440p in Cyberpunk with ray tracing — GPU at 99%, CPU at 50%. Swap to Valorant at 1080p competitive settings, and suddenly the CPU is working hard to push 300+ FPS while the GPU barely breaks 60% utilization. Same hardware, completely different bottleneck behavior.

The game, resolution, and target framerate all change the equation.

Esports titles at high framerates are almost always CPU-bound. Open-world and graphically complex games at higher resolutions are usually GPU-bound. This isn’t a problem — it’s how these systems are supposed to work.

Before upgrading anything, use our PC Bottleneck Calculator to plug in your current CPU and GPU combination and see how they pair on paper. It helps frame the decision before you start pulling components.

Optimization Before You Spend Money

I’ve seen people drop $400 on a new GPU when all they needed to do was clean their PC and update their drivers.

Try these first:

• Close background processes. Discord, browser tabs, streaming software — these eat CPU cores that games need. Kill them and retest.
• Update GPU drivers. A bad driver release can tank performance in specific titles overnight.
• Check RAM configuration. If you have 16GB in one slot instead of two (dual-channel), you’re leaving 15–20% performance on the table in memory-sensitive games.
• Adjust in-game settings. Shadows and draw distance are CPU-heavy. Dropping these while keeping resolution scaling high lets the GPU work more and the CPU work less.
• Reapply thermal paste. If your system is 3+ years old and throttling, this $8 fix can recover 10–15% clock performance.

Common Myths Worth Killing Off

“Any bottleneck is bad.” False. A GPU bottleneck at your target resolution means your build is balanced correctly. The GPU should be the limiting component in graphically demanding games.

“The bottleneck calculator online gives you the answer.” These tools estimate, they don’t measure. Real testing inside games, with monitoring software running, always tells you more. That said, a good pairing tool is genuinely useful for planning a new build — and our full guide to bottleneck calculators breaks down how to use those estimates correctly alongside live monitoring.

“100% CPU usage always means you need a new CPU.” Not necessarily. It depends on which game, what settings, and what framerate you’re targeting. Some games just push CPUs hard — that’s not the same as having a bad processor.

If you want to understand which tools give the most reliable estimates and why the percentages vary between them, our breakdown of the best PC bottleneck calculators covers exactly that.

Troubleshooting Checklist

Before concluding you have a bottleneck problem, run through this:

• MSI Afterburner overlay running during gaming session
• GPU usage confirmed (above or below 95%)
• CPU usage checked per-core in Task Manager (Advanced view)
• CPU temps monitored under sustained load via HWMonitor
• Background processes closed during test
• RAM running in dual-channel
• Drivers updated in last 30 days
• Thermal paste less than 3 years old
• Tested with at least two different games at different settings

FAQ

How do I find my CPU to check its performance?

Open Task Manager > Performance > CPU. Your processor model is listed at the top right. For more detail, download CPU-Z.

How much GPU usage is normal during gaming?

95–99% at your target settings and resolution is ideal. Anything below 80% with low FPS means something else is limiting the GPU — usually the CPU.

How do I fix a CPU bottleneck without replacing it?

Close background processes, run in dual-channel RAM, lower CPU-heavy settings like shadows and draw distance, and make sure your CPU isn’t thermal throttling. If it is, improve cooling first.

Can bottlenecking damage your hardware?

Sustained thermal throttling over long periods does add heat stress. Keeping components within their rated thermal limits matters for long-term stability.

Is Fortnite CPU or GPU heavy?

Fortnite scales with both, but at higher framerates (144Hz+) it becomes increasingly CPU-dependent. A faster processor will have more impact here than in slower-paced graphical games like Cyberpunk 2077.