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What is a PC bottleneck, and how do I avoid one?

What is a PC bottleneck, and how do I avoid one?

For decades, PC enthusiasts have been roving around their systems looking for and fixing GPU and CPU issues. The reason is simple: throttling can cut you off from your computer’s additional performance.

That’s why it’s important to understand what a bottleneck is, how to find it, and how to avoid it in the future.

What is the PC bottleneck?

Diagram of a bottleneck in a computer.
Taylor Frent/Digital Trends

Throttling occurs in your computer when one component limits the performance of another component. It’s a simple premise, but the bottlenecks in a real computer are complex and multi-layered. Every computer has bottlenecks at several points, often within each component.

For PC gamers, the main concern is the throttling that can occur between the CPU and the GPU. These two components depend on each other to display the final image you see on the screen, and throttling occurs when one lifts the other up.

For easy numbers, imagine that the CPU and GPU each have 1/120 of a second to perform their tasks. This means that you have a frame every 1/60th of a second (or 60 frames per second). If your GPU can keep up with that pace, but your CPU can’t, you have a CPU bottleneck. Likewise, if your CPU is sending instructions at a fast pace, but your GPU is struggling to render the frame in time, you have a GPU bottleneck.

A good real example of this comes from our own criteria. At 4K with the RTX 3090, we scored nearly identical results between the 10-core Intel Core i9-10900K processor and the 16-core Core i9-12900K in Forza Horizon 4 – Only a 1.2% difference in our average frame rate. However, at 1080p resolution, these processors show a more significant 15.6% difference in the average frame rate.

Diagram showing an example of a bottleneck in a GPU.

This is an example of a bottleneck in a GPU. At 4K the graphics card runs as fast as it can, so it doesn’t matter how powerful the processor is – it will always be limited by the GPU. By reducing the resolution to 1080p, and thus the load on the graphics card, processors show more differences because they are no longer restricted to the GPU.

That’s why our processor ratings show results in 1080p, even with $800 CPUs like the Core i9-12900KS. Likewise, that’s why we’ve paired budget GPUs like the RTX 3050 with more expensive CPUs like the Ryzen 9 5950X. All in an effort to avoid bottlenecks.

How do you find the bottleneck in your computer?

Core i9-12900KS processor socket on the motherboard.
Jacob Roach / Digital Trends

It’s easy to find the bottleneck in your computer. All you have to do is monitor your CPU and GPU usage and from that, you can infer if you have a bottleneck in your system. I recommend downloading MSI Afterburner (also useful for GPU overclocking) to keep a detailed log of CPU and GPU usage, but you can easily monitor these metrics while playing a game using tools like Nvidia’s GeForce Experience overlay.

If your CPU usage is much higher than your GPU usage, this indicates CPU throttling and vice versa. Any use of less than 50% is considered low, 50% to 70% is normal, and 70% and above is considered high. These are just approximate numbers, so don’t take them as a bottleneck. If you see 60% GPU usage and 80% CPU usage in a game, for example, you might have a slight CPU bottleneck, but that’s not something you should worry about.

MSI Afterburner window with monitoring information.

To register use, download and install MSI Afterburner. Open it and follow these steps:

  1. Click settings.
  2. select file watching tab.
  3. under Active hardware monitoring graphs, to specify GPU usage And using the processor. You can also include other metrics in your log file if you wish.
  4. under hardware monitoring log logging properties, check the Log archives in a file Box.
  5. (my choice) global screen hot keys, Set hotkeys to start and stop recording, as well as clear history.
  6. click Progressing.

With MSI Afterburner set up, start playing some of the games you usually play. Clear history history by right-clicking on the screen and selecting clear date, then select Log archives in a file. Alternatively, you can do it using hotkeys if you set them up in the previous step.

Play the game for about 30 minutes and then open your log file. By default, you will find it here: C: / Program Files (x86) / MSI Afterburner / HardwareMonitoring.hml. Afterburner stores several records in this file, so you’ll need to select the one you want to view.

Ideally, you’ll repeat this process with several games to emphasize your components differently. If you see a big gap between usage – let’s say 90% CPU usage and 50% GPU usage – you have a bottleneck.

I wouldn’t recommend using one of the many calculators you can find online. These calculators do not represent real world performance, and they are not relevant to finding the bottleneck in the specific hardware configuration. The best way to find out is to check yourself.

How to fix and avoid PC crisis

NVIDIA GeForce RTX 3000
Javier Esteban on Unsplash

The best way to fix a bottleneck in a PC is to upgrade your hardware. If you are using an Intel Core i7-4770K processor, and have a modern GPU, you will need to choose one of the best gaming processors. Likewise, if you have a modern CPU with a large number of cores but a weaker video card, you will need to upgrade with one of the best graphics cards.

However, money is not unlimited, so there are some things you can do to reduce the bottleneck. One option is to overclock your weakest component to get some extra performance out of it. You can also tweak the game settings or lower the resolution to reduce the bottleneck in the GPU.

To avoid suffocation, be sure to balance your devices. With modern GPUs and CPUs, this should be fairly straightforward. If you pair the RTX 3080 with a Core i3-8100, for example, you’ll experience a CPU crunch. The goal of chokes is to avoid wide gaps as you pair a modern, high-quality component with a low-end component that is several generations old.

Logo on the RTX 3090.
Jacob Roach / Digital Trends

Not all jams are a cause for concern, either. For example, you will always have a GPU bottleneck when playing at 4K, but that’s only because 4K is so demanding of modern graphics cards. The only time it’s a PC throttling issue is when you’re getting far less performance from a component than it should.

Don’t worry too much about jams

Dedicated water cooling inside the gaming PC.
Jacob Roach / Digital Trends

Although the idea of ​​restricting your devices through a bottleneck is intimidating, you shouldn’t pay much attention to it. Even a computer with the latest and most expensive hardware will face many bottlenecks all the time. The most important time to consider bottlenecks is when you are about to upgrade your computer to avoid spending a lot of money on a component that your hardware can’t take full advantage of.

I’ve focused on CPU/GPU dynamics in gaming PCs here, because that’s where you’ll see the clearest signs of throttling. In some cases, you may see it elsewhere on your device. If you’re using a memory-intensive application like Adobe Premiere Pro, for example, your high-core processor may be throttled by not having enough RAM.

The best advice is to just keep the jams in mind. They can help make upgrade decisions, but you shouldn’t look for them if you’re happy with your PC’s performance.

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