Modern videogames need a combination of a powerful GPU paired with a fast CPU to run in the best possible way. When one of the two components are weak, they can throttle the performance of your overall system and prevent it from running games smoothly.
It can appear in games as either poor frame-rates, massive dips in frame-rates during certain events, and much more. The term used for this is GPU or CPU bottleneck.
What is a Bottleneck?
Bottleneck is a term to describe the reduction in speed or amount of data processed by a computer because one of the components of the system is holding the rest of the system back.
This is when the output of processed data of the entire system is too slow compared to the input because of one component that can’t keep up with the rest of the system. The two main components involved in the process of bottlenecking in videogames are the CPU and GPU. These two PC parts are the core processing units, handling different tasks in videogames to bring you the image on your screen. If one of them is significantly slower than the other, the performance of the videogames is greatly affected.
The central processor bottleneck is more common of the two bottleneck types observed in videogames. This often happens when a slow CPU is paired with a more powerful GPU. Since the CPU cannot process the data fast enough to keep up with the GPU, it bottlenecks the overall performance of the computer in games.
Let’s say you paired an Intel Pentium processor with an Nvidia RTX 2060. The RTX 2060 is powerful enough to run most games at both 1080p and 1440p resolutions with absolute ease. However, you’ll find the game has stutters, jitters, and much frequent performance drops as the CPU is too slow to keep up with the speed of the GPU. This is a CPU bottleneck, as the CPU is the limiting factor in your videogame’s performance.
Graphics card bottleneck is more easily addressed than CPU bottlenecks and is found when a powerful CPU is paired with a weak graphics card. For example, if you pair a Core i7 9700K with a GT 1030, you will find massive dips in performance in your videogames because the central processor is too powerful, while the GT 1030 lacks the power to keep up. The limiting component for processing data fast enough is the GT 1030 here as it simply can’t keep up.
How to Determine Which Component is Bottlenecking
There is no direct way to know just by playing the game whether it’s your PC’s CPU or GPU that is bottlenecking. Although the effects of each bottleneck type are discrete, it is difficult to determine it without any tools.
Luckily, tools to determine which component is causing the bottleneck are widely available. The MSI Afterburner is one of the best ways to determine which part of your rig is causing the bottleneck easily.
Simply open the program in the background and play a videogame of your choice. If the CPU is constantly at 100% usage while the GPU is around 90% or less, then this is a CPU bottleneck. On the other hand, if your GPU is stressed constantly at 100% but your CPU is under 90%, then this is a GPU bottleneck.
If you are concerned about bottlenecking before building your PC and aren’t sure the components you’ve chosen will cause bottlenecks, you can check out The Bottlenecker’s Bottleneck Calculator.
In-game Effects of CPU and GPU Bottlenecks
The CPU is responsible for physics, UI, processing real-time game actions, audio, and other complex CPU-bound processes. When a CPU is too slow to keep up with a powerful graphics card, it can result in serious stutters, frame-rate drops, and hang-ups. This happens when physics and real-time game action data becomes more complex.
Think of when you kill an entire mob of enemies with a huge explosion and their remains scatter all over. While the graphics card handles the textures, animations, and overall visual processing of the scenario, the calculations of the physics and real-time game action are done by the CPU. If your CPU is not as fast as your CPU, you’ll see a massive frame-rate drop during the entire explosion scenario as the CPU fails to do its job in time.
A GPU bottleneck will simply result in very poor frame-rates. A GPU bottleneck thus is considered more tolerable as simply lowering the graphics quality can show a great improvement in the videogame’s performance.
CPU Bottleneck Solutions
CPU bottleneck is the most challenging to deal with, as it’s not as easy to replace a CPU or address it as is with a GPU bottleneck. Here are some ways to reduce CPU bottleneck:
Reduce Number of Background Processes – Your CPU is often running much additional software in the background while you play games as well. To reduce the load on the CPU, close all non-essential background applications.
Increase Game Resolution – This may sound counter-intuitive, but one of the easiest ways to reduce CPU bottleneck is to increase your videogame’s resolution. By doing so, the GPU will need more time to render higher resolution graphics. This will give time for your slow CPU to catch up. You’ll observe a drop in frame-rates, but the consistency of the gameplay will be a lot better.
CPU Overclocking – If your CPU can overclock and you have the right cooling solution for it, boosting the core clock speed of your CPU will make it faster in processing data. This will reduce the major difference in speeds between the GPU and CPU, so it becomes a little easier for your CPU to keep up.
Lower CPU-intensive Settings – We’re talking about settings like draw distance, population densities, physics, vegetation, and others.
Replace with a more Powerful CPU – The last step you could consider is replacing your entire CPU. This is an invasive and costly solution, but a permanent one.
GPU Bottleneck Solutions
When it comes to GPU bottlenecking, there aren’t as many techniques available as there are for CPU. A few suggestions are:
Lower Graphic Settings – Lowering GPU intensive settings like antialiasing, texture resolutions, general resolution, effects, post-processing, and others is the main way to reduce GPU bottleneck.
Overclock GPU – You can choose to overclock your GPU’s core speed as well as memory speed to improve its performance. However, do note that GPUs don’t overclock as drastically as CPUs do and are much more sensitive to even small boosts, so be careful with it!
Replace Your GPU – Yeah, this is again an expensive step, but it’s actually the most preferred by many gamers. Modern mid-range and high-end GPUs are all powerful enough to run adequately when paired with powerful CPUs, so upgrading is a sure-bet to greatly reduce or completely eliminate graphics card bottleneck.
Videogames and Bottlenecking
Yes, you read that correctly. Certain videogames will cause CPU bottlenecks while others cause GPU bottlenecks. This isn’t really a concern if you pair a very powerful processor with a very powerful graphics card (like a Core i9 9900K with a 2080 Ti), but if you have mid-range CPU and GPU, you’ll see a greater variation in the bottleneck type.
Each videogame is designed differently. Some are more CPU dependent while others are more GPU dependent.
CPU dependent games will put more load on the CPU, increasing the chances of a CPU bottleneck. Examples of such games include ones with more processor-intensive tasks such as Cities: Skylines, Minecraft, Assassin’s Creed: Black Flag, and more.
GPU dependent games are usually the ones with the most eye-candy. These videogames often look absolutely gorgeous and as a result demand a powerful graphics card to run. Examples of such games are Shadow of the Tomb Raider, Far Cry 5, The Witcher 3, and more.
We learn from this that CPU and GPU bottleneck isn’t solely limited to the components itself. It is, however, true that the component plays a major part, and the best overall solution is to get a combination of a great CPU and a great GPU.