Bottleneck Test / PC: How to Check and Fix CPU & GPU Bottlenecks for Maximum Performance

When building or upgrading your gaming PC, one of the biggest performance killers is a bottleneck — a mismatch between your CPU and GPU that prevents your hardware from performing at its best.
That’s why every gamer and PC enthusiast should know how to perform a bottleneck test on their PC.

In this guide, you’ll learn exactly how to test your PC for bottlenecks, what tools to use, and how to fix CPU and GPU bottlenecks to get the most out of your system.

What Is a PC Bottleneck?

A PC bottleneck occurs when one component of your system limits the performance of another.
In most cases, the CPU (Central Processing Unit) or GPU (Graphics Processing Unit) is responsible.

For example:

• If your CPU cannot keep up with your GPU, your graphics card will not reach its full potential.
  
  
• If your GPU is weaker than your CPU, the graphics card becomes the limiting factor.
  
  

This imbalance reduces your FPS (frames per second), causes stuttering, and leads to lower gaming performance overall.

Why You Should Run a Bottleneck Test on Your PC

Performing a bottleneck test for PC is essential for anyone who:

• Builds custom gaming PCs
  
  
• Upgrades graphics cards
  
  
• Wants to get the most FPS and performance out of their hardware
  
  
• Streams or edits videos using CPU-intensive tasks
  
  

A bottleneck test helps you:

1. Identify which component (CPU or GPU) limits your performance
   
   
2. Understand how well your PC parts work together
   
   
3. Make informed upgrade decisions
   
   
4. Optimize your gaming setup without wasting money
   
   

How to Test for Bottlenecks on Your PC

There are two main ways to perform a bottleneck test on your PC:

1. Using software tools and benchmarks
   
   
2. Using an online bottleneck calculator
   
   

Let’s explore both in detail.

1. Using Bottleneck Test Software Tools

These tools give you real-time information about your CPU, GPU, and overall system performance.

a. MSI Afterburner

One of the most popular and reliable tools for monitoring PC performance.
You can track:

• CPU usage
  
  
• GPU usage
  
  
• FPS
  
  
• Temperature
  
  

👉 If your GPU usage is at 99–100% while your CPU usage is below 70%, you have a GPU bottleneck.
👉 If your CPU usage is at 100% but your GPU usage is low, it’s a CPU bottleneck.

b. HWMonitor

A lightweight tool to check CPU temperatures, core utilization, and power usage — helpful for diagnosing CPU bottlenecks or thermal throttling.

c. 3DMark / Unigine Heaven

Use these benchmarking tools to simulate gaming loads.
Compare your FPS results and GPU scores with online databases to identify bottlenecks.

d. Windows Task Manager

Press Ctrl + Shift + Esc → Go to Performance Tab.
Monitor CPU and GPU activity while gaming — a simple but effective bottleneck test for PC.

2. Using Online GPU/CPU Bottleneck Calculators

If you prefer a quick and simple way, use a GPU Bottleneck Calculator or CPU Bottleneck Test Tool online.

Popular options include:

• PC-Builds Bottleneck Calculator
  
  
• CPU Agent Bottleneck Tool
  
  
• Build Redux Bottleneck Estimator
  
  

You simply enter your:

• CPU model
  
  
• GPU model
  
  
• RAM amount
  
  
• Screen resolution
  
  

The tool calculates your bottleneck percentage — for example:

• “5% CPU bottleneck” → Great balance
  
  
• “20% GPU bottleneck” → Your GPU is slightly limiting performance
  
  

These tools are highly useful for pre-build planning or upgrade evaluation.

Common Causes of PC Bottlenecks

1. CPU Bottleneck

A CPU bottleneck happens when your processor cannot process game data fast enough to keep your GPU fully utilized.
Common in high-FPS, CPU-intensive games like:

• Fortnite
  
  
• Valorant
  
  
• Counter-Strike 2
  
  
• PUBG
  
  

2. GPU Bottleneck

A GPU bottleneck occurs when your graphics card struggles to keep up with the CPU, especially in graphically demanding games like:

• Cyberpunk 2077
  
  
• Hogwarts Legacy
  
  
• Red Dead Redemption 2
  
  

3. RAM Bottleneck

Low RAM capacity or slow RAM speed can also cause performance drops.
Always use at least 16GB DDR4 or DDR5 RAM at 3200MHz or higher.

4. Storage Bottleneck

If your game is installed on a slow HDD instead of an SSD, loading and texture streaming may cause frame dips and stuttering.

5. Power or Thermal Throttling

Insufficient power supply or poor cooling can limit GPU boost clocks and cause thermal bottlenecks.

How to Fix CPU and GPU Bottlenecks

Once you’ve identified the cause using a bottleneck test, here are practical solutions:

1. Adjust Graphics Settings

• Lower resolution or graphics quality
  
  
• Disable ray tracing
  
  
• Enable DLSS, FSR, or XeSS
  
  
• Cap frame rate to reduce CPU load
  
  

2. Overclocking

• Use MSI Afterburner or Intel XTU to safely overclock your GPU or CPU
  
  
• Improves performance by 5–15% in some cases
  
  

3. Upgrade Components

• Replace your CPU with a higher-core model
  
  
• Upgrade your GPU if it’s too weak for your resolution (e.g., move from GTX 1660 to RTX 4070)
  
  
• Add faster or more RAM
  
  

4. Optimize Background Tasks

• Close Chrome, Discord, or OBS while gaming
  
  
• Disable startup programs and Windows Game Bar
  
  

5. Improve Cooling and Power

• Use a quality PSU (Power Supply Unit)
  
  
• Clean your fans and ensure good airflow
  
  
• Re-apply thermal paste if needed
  
  

Understanding Bottleneck Percentage

Best Tools for Bottleneck Test / PC

Frequently Asked Questions (FAQ)

1. What causes a bottleneck in a gaming PC?

A bottleneck happens when one part, like the CPU or GPU, is much slower than the other, preventing balanced performance.

2. Can I fix a bottleneck without upgrading hardware?

Yes — adjusting graphics settings, overclocking, and closing background tasks can reduce bottlenecks.

3. How accurate are online bottleneck calculators?

They give a good estimation but are not 100% precise. Always cross-check with real-time monitoring tools like MSI Afterburner.

4. What is a good bottleneck percentage?

Anything below 10–15% is ideal and means your PC build is well balanced.

5. Does RAM speed affect bottlenecks?

Yes — slow RAM can limit both CPU and GPU performance, especially in open-world games.

Final Thoughts

Running a bottleneck test for your PC is one of the smartest steps you can take to ensure balanced and efficient performance.
By identifying whether your CPU, GPU, or RAM is holding you back, you can fine-tune your setup, upgrade wisely, and enjoy smoother gaming and rendering experiences.

So before spending hundreds on upgrades, try a bottleneck test / PC analysis first.
You’ll know exactly where your system stands — and how to get the best possible performance out of it.