Limit FPS

The scope of this guide is to introduce some basic tools and provide instructions on how to use them to limit your FPS in games. Teaching how to fully utilise these tools or troubleshooting is beyond the scope of this guide. If you want to learn more about a tool refer to their respective user manual. If you're having issues then open up your search engine of choice and start searching.

NVIDIA Control Panel
Open the NVIDIA Control Panel by right clicking on your desktop to bring up the context menu and then click on the NVIDIA Control Panel option. From there follow these instructions:

1. Open "3D Settings"
2. Open "Manage 3D Settings"
3. Open "Global Settings" for global settings or "Program Settings" for local settings. If you chose local then find and select the exe of the program.
4. Find the "Max Frame Rate" option, turn it on, and input your desired limit.

AMD Software: Adrenaline Edition
Open AMD Adrenaline by right clicking on your desktop to bring up the context menu and then click on the AMD Adrenaline option. From there follow these instructions:

1. Open the "Gaming" tab
2. Open "Games" for local settings or "Graphics" for global settings. If you selected "Games" then select a game from the list.
3. Find "Radeon Chill", turn it on, and input your desired limit. Unless you have reason to do otherwise, just set the minimum to the same value as your maximum.

MangoHud
Follow the installation instructions on MangoHud GitHub[github.com]

MangoHud comes with a config file which can be used to set configuration options globally or per application. Usually it is installed as or get a copy from here[raw.githubusercontent.com]. For global configuration (won't affect programs unless instructed to), create
For per-application configuration create one of the following

Note from README.md:

Using a text editor, open the configuration file you will be using and find the environment variable "fps_limit" and set the value to your desired limit, save.

Before I have been blessed with the knowledge on how to fps limit games externally I had to search for it like the rest of you and too often I came across people recommending to use v-sync to limit fps. This is terrible advice in the context of fast paced first person shooters, like doom eternal, as it introduces input lag which hinders your ability to perform well. The purpose of v-sync is to eliminate screen tearing by syncing the frame rate with your monitors refresh rate, fps limiting is a byproduct of this and not the primary goal. Stop recommending this for FPS games you filthy casual!

Are you getting good FPS but the game still feels off? It could be you are getting poor frame times.

Frame Rate vs Frame Time
Frame rate, measured in fps, is the average number of frames rendered in a second.
Frame time, measured in milliseconds, is the time between each frame when no new frame has been rendered yet. If the frame times are above the maximum threshold it will completely ruin the feel of a game even if the frame rate is decent.

What is the maximum threshold?
The maximum threshold is 1/fps * 1000 where fps is the frame rate at which you are playing.
For example, if you are playing at 60fps your frame times should not exceed 16.6ms.

Ideally you want your frame rate as high as possible and frame times as low as possible.

How to see your frame times?
On Windows you can use MSI Afterburner to do so. Covering the installation, setup, and usage of MSI Afterburner is beyond the scope of this guide.
On Linux you can use MangoHud to see your frame times by making sure the "frametime" environment variable is uncommented in your configuration file.

What to do about bad frame times?
You could buy better hardware but ultimately poor game optimisation will give even the high end a hard time, as AAA games love to prove over and over again in the 2020s.

The most accessible solution to this problem is increasing the frame rate. By increasing the number of frames being rendered in a second there is less time being spent waiting for a new frame. If this is not an option then the game is either not optimised enough to deserve your time and money or you should start thinking about saving up for better hardware if you're convinced otherwise.