How to Find & Fix a CPU or GPU Bottleneck

This guide helps you identify whether your CPU or GPU is limiting your PC’s gaming performance and shows you practical steps to fix or reduce the bottleneck. You’ll learn how to monitor your hardware, interpret the data, and apply both software and hardware adjustments to get the most out of your system.

What You’ll Need

• A PC running Windows 10 or 11 (the steps are similar on other OSes, but the tools may differ)
• Administrator access to install software and change system settings
• Monitoring software: MSI Afterburner (free) or the built-in Windows Task Manager and Performance Monitor
• A benchmarking tool or a demanding game to stress your system
• Optional: a second monitor to keep an eye on metrics while gaming

Step-by-Step

1. Understand what a bottleneck is. A bottleneck occurs when one component (CPU or GPU) is significantly slower than the other, causing it to max out while the other waits. For gaming, a CPU bottleneck means the CPU can’t keep up with the GPU, so the GPU isn’t fully utilized. A GPU bottleneck is the opposite – the GPU is the limiting factor, which is actually the ideal scenario for most games.
2. Install monitoring software. Download and install MSI Afterburner (it works with any GPU, despite the name). During installation, also install RivaTuner Statistics Server (RTSS), which comes bundled and allows you to display on-screen metrics. Alternatively, you can use Windows’ built-in tools, but they are less detailed.
3. Configure on-screen display (OSD). Open MSI Afterburner settings, go to the “Monitoring” tab, and enable the following metrics to show on your OSD: GPU usage, GPU temperature, CPU usage (per-core), CPU temperature, and framerate. Check the “Show in On-Screen Display” box for each. Set a hotkey to toggle the OSD (default is often Ctrl+O).
4. Run a stress test or a demanding game. Launch a game that is representative of what you usually play, or run a benchmarking tool like 3DMark or Unigine Heaven. Play or run the test for at least 15–20 minutes to get stable readings. If you have a second monitor, you can also watch the metrics there.
5. Interpret the data. While the test is running, look at the OSD. If your GPU usage is at 95–100% and your CPU usage is lower (e.g., 50–70%), you have a healthy GPU bottleneck – the GPU is working as hard as it can. If your GPU usage is below 90% (especially if it’s fluctuating) and one or more CPU cores are at 90–100%, you have a CPU bottleneck. A CPU bottleneck often shows as lower framerates than expected, even with a powerful GPU.
6. Confirm with a second method. For a more precise check, use a tool like CPU-Z to monitor per-core usage. In a CPU bottleneck, you’ll see one or two cores maxed out while others are idle. Also, lower your resolution and graphics settings: if your framerate doesn’t improve much, it’s a CPU bottleneck; if it jumps up, it’s a GPU bottleneck.
7. Fix a CPU bottleneck:
   • Close background programs: Close browser tabs, streaming software, or other apps that use CPU resources.
   • Overclock your CPU: If your CPU and motherboard support it, overclocking can increase performance. Be careful and follow guides specific to your hardware.
   • Increase resolution or graphics settings: This shifts more load to the GPU, which may balance the load and improve overall smoothness (even if the framerate drops slightly, it can reduce stuttering).
   • Upgrade your CPU: If the bottleneck is severe, you may need a newer, faster CPU with more cores and higher single-thread performance.
8. Fix a GPU bottleneck:
   • Lower graphics settings: Reduce resolution, turn off anti-aliasing, shadows, and other demanding effects.
   • Update GPU drivers: Ensure you have the latest drivers from NVIDIA or AMD.
   • Overclock your GPU: Use MSI Afterburner to increase core clock and memory clock, but do so incrementally and test stability.
   • Upgrade your GPU: If you want higher framerates, a more powerful GPU is the solution.

Common Mistakes

• Looking at total CPU usage instead of per-core. A game might use only one core, so total CPU usage could be 30% while that core is at 100%. Always check per-core usage.
• Testing with vsync enabled. Vsync caps your framerate, which can artificially lower GPU usage and make it look like a CPU bottleneck when it’s not. Disable vsync during testing.
• Not using a consistent test. If you change games or settings between tests, you can’t compare results. Use the same game and settings for before/after comparisons.
• Assuming a bottleneck is always bad. A GPU bottleneck is normal and healthy. The goal is to have the GPU at 100% and the CPU not maxed out.

Tips

• Use a frame time graph. Instead of just framerate, look at frame times (in milliseconds). Spikes in frame time indicate stuttering, which is often a sign of a CPU bottleneck.
• Test with different resolutions. Run the same scene at 1080p and 1440p. If the framerate drops significantly at higher resolution, the GPU is the limit; if it stays the same, the CPU is the limit.
• Consider RAM and storage. A slow hard drive or insufficient RAM can cause stuttering that mimics a bottleneck. Ensure you have enough RAM and use an SSD for games.
• Check thermals. If your CPU or GPU is overheating, it will throttle down, causing performance drops. Monitor temperatures (CPU under 90°C, GPU under 85°C is generally safe) and clean your PC’s fans if needed.

Troubleshooting

• If you don’t see any metrics in the OSD: Make sure you enabled the “Show in On-Screen Display” for each metric in MSI Afterburner settings. Also, ensure RTSS is running (look for the icon in the system tray). If you’re using a different overlay tool, check its own settings.
• If your framerate is low but neither CPU nor GPU is at 100%: This could indicate a power limit, thermal throttling, or a driver issue. Check your power plan is set to High Performance, and update your chipset drivers.
• If you suspect a CPU bottleneck but upgrading isn’t an option: Try capping your framerate slightly below your CPU’s limit (e.g., using RTSS to cap at 60 FPS if your CPU can handle 60). This can reduce stuttering and make the experience smoother.
• If you overclock and get crashes: Reset to stock settings and re-test. Overclocking is not guaranteed; your chip may not handle the overclock. Always test stability with a stress test like Prime95 (for CPU) or FurMark (for GPU) for at least 30 minutes.

Frequently Asked Questions

What is the ideal CPU and GPU usage during gaming?

Ideally, your GPU should be at 95–100% usage, and your CPU should be below 80–90% on any single core. If the GPU is below 90% and a CPU core is maxed out, you have a CPU bottleneck.

Can a bottleneck damage my PC?

No, a bottleneck is not harmful. It simply means one component is limiting the other’s performance. It doesn’t cause damage, but it can cause stuttering or lower framerates.

Is a CPU bottleneck worse than a GPU bottleneck?

Generally, yes. A GPU bottleneck means your GPU is working as hard as it can, which is what you want. A CPU bottleneck can cause frame drops and stuttering, and is often harder to fix because it may require a CPU upgrade.

How do I know if I need to upgrade my CPU or GPU?

Use the monitoring steps above. If your GPU is at 100% and you want more FPS, upgrade the GPU. If your CPU is maxed out on one or more cores and your GPU is not fully utilized, upgrade the CPU.

Will overclocking my CPU or GPU help with a bottleneck?

Overclocking can help, but it won’t eliminate a severe bottleneck. It may give you a 5–10% performance boost, which can be enough to reduce stuttering, but if one component is much older than the other, an upgrade is more effective.

Can I fix a bottleneck with software settings?

Sometimes. Lowering graphics settings can reduce GPU load, which may help if you have a GPU bottleneck. For a CPU bottleneck, closing background programs and capping your framerate can help. But if the bottleneck is due to hardware limitations, software tweaks have limited effect.

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