A CPU bottleneck occurs when your CPU stops your GPU from functioning at its maximum potential. Similarly, a GPU bottleneck occurs when your GPU slows down its processing speed thereby impacting your CPU’s processing speed.
Therefore, the amount of data that needs to be processed is higher than the total data queued up for processing.
While playing games if you are suddenly interrupted by a blurry screen and drop in FPS (Frames Per Second) your CPU could be bottlenecking your GPU.
If you are wondering why CPU bottleneck GPU while experiencing frequent interruptions in your tasks, read on to diagnose and troubleshoot.
In This Article
10 Reasons Why CPU Bottlenecks GPU (with Fixes)
1. Background Processes
Background processes are applications that operate in the background, oftentimes without a user knowing that they are actively running.
For instance, your computer has several applications installed on it including an anti-virus software.
This program is always active and running, however, most users tend to forget that it is running as a background process on your CPU.
This application has permission to scan each and every action performed by your computer, thereby making it possible for it to keep your device protected from viruses.
All processes which are visible through Task Manager, as well as all connected peripherals are scanned through this application to ensure security.
Regardless of whether you are connecting a USB device or are browsing the internet, anti-virus programs actively scan all actions without requiring your permission for each action.
All of these actions are being performed by your CPU, since it is your CPU’s responsibility to handle all such background processes.
Additionally, your CPU needs to keep giving commands to this application while ensuring data flow takes place properly.
Your CPU is also responsible for keeping your computer up and running by ensuring all processes are allocated necessary resources including memory and processing power.
Since, your processor has to actively run all background processes, even if they are considered as simple background processes by users.
A CPU is made up of millions of very small transistors. These transistors act as switches which can be turned on/off to send signals to all components connected to your CPU.
These messages are communicated through passing of electricity to either send a yes or no message for every action that needs to be performed.
If you run a gaming application or CPU resource-intensive task, especially when there are too many background processes using your CPU’s processing power, your CPU will struggle to allocate sufficient resources to all applications, thereby affecting its processing speed.
This in turn bottlenecks your GPU, as it cannot move forward without receiving instructions from your CPU.
While your CPU is sending instructions to your GPU slowly, your GPU is forced to underperform by remaining idle. This wasting and limiting of your GPU’s processing power and speed is bottlenecking its potential.
This can be prevented by ensuring your CPU has enough processing power required to run one resource-intensive application and several background processes.
Furthermore, by having plenty of background processes, it is not only your CPU which affects your GPU but all internal components do as well.
Once the CPU is overloaded with tasks, it starts using your device’s main memory temporarily to perform several other tasks simultaneously.
In this way main memory does not send required graphical data quickly, since it is busy acting as primary memory and temporary processor.
In order to ensure it is actually your CPU’s background processes causing this issue, open Task Manager and check how much processing power all actively running processes are consuming.
If the total percentage of consumption of CPU’s processing power is more than 90%, you can be sure that unnecessary and resource consuming background processes are responsible.
There are two ways to solve this issue once you have determined a cause. You can either upgrade to a better CPU, with higher processing power and speed or stop some processes from running as background processes.
There are several processes which often sneakily obtain permission to start running as soon as your computer is turned on.
If you do not check carefully while installing any applications, these programs will keep running on your CPU and consuming its processing power as long as your computer is powered on.
Go to Task Manager and under applications tab observe which applications were not started by you and are not being currently used by you.
Make a list of these names and start ending all of these unnecessary applications. Now, click on the Start-Up tab in Task Manager and view all applications that have permission to start as soon as your computer is turned on.
Click on every option and disable processes which consume too much power at start-up.
2. Gaming at 1080p
Most gamers prefer setting resolution for their games to 1080p even though their computer system is able to perform at better resolutions as well.
Graphics settings are relaxed and it increases a game’s performance on a computer system. FPS is the most important factor when gaming as a clear view of game scenes is necessary to understand what a player’s next move should be.
Frames per second or FPS is a method of measuring the number of frames that can appear on video games, video captures and playback.
It is generally used for measuring a display device’s performance and video quality. For instance, at 30 FPS, within a second, 30 distinct images appear one after another on a display screen.
While a human brain only has the ability to process about 10 to 12 FPS, higher FPS rate helps in video or motion creation.
An FPS rate greater than 24 FPS produces videos with complete motion, and when FPS rate increases further, it produces an even smoother picture.
Conversely, low frame rates make motion appear jerky and jagged. A very high frame rate could result in blurry images as well, since your processor and display might not be able to handle functioning at this speed.
Every application on your computer, be it a simple calculator or a graphic-intensive game, requires CPU resources to run.
Even though your GPU handles most of your system’s graphical data processing, your CPU needs to perform a lot of tasks in order for any application to run smoothly. Therefore, your CPU plays a major role when gaming at 1080p.
In order to understand how CPU bottlenecks GPU while gaming at 1080p, it is necessary to understand how GPU affects your gaming experience.
When you run a gaming application, it is your GPU’s duty to create all visuals of all objects in a game. Additionally, it also handles visual effects, textures, reflections, lighting effects and positions of objects.
If you have a high-end GPU, it is fairly possible for it to get bottlenecked by your CPU, especially if you are using an older computer.
Since your GPU handles all important graphics related tasks, you might feel that your CPU does nothing, however, your CPU is responsible for handling all movements of any and all game related graphical objects.
Each object has vertices and edges, and whenever one of these objects moves, your CPU changes location of its vertices.
Your CPU is also responsible for handling all in-game logic and this cannot be done by your GPU alone. When any action is performed in a game, your CPU receives instructions from game data to take a particular action in response.
This data is then used for calculating score as well as communicating to your GPU what objects must change in this game’s next frame or scene.
If your CPU is unable to gather this data quickly, process it according to game logic and then forward it to your GPU to create game characters and objects along with suitable textures, reflections, positions and lighting, it affects FPS.
Your GPU does not receive graphics information in time. Even though due to its parallel processing, data will be processed very quickly, your GPU does not receive enough data to perform at its optimal speed.
At 1080p, 1440p and 4k, CPU has to perform equally, and there is not a lot of difference between CPU’s processing power and time consumed at every resolution. However, at higher resolutions GPU is unable to process faster.
CPU bottlenecks GPU at 1080p because GPU can process graphical data at higher speeds, but is not allowed to as CPU limits its speed owing to its limited processing power.
There are two solutions to this issue, either upgrade your CPU or change game resolution.
If you are serious about gaming or video editing, and have specially purchased a gaming computer or are considering purchasing a gaming computer, you should choose a CPU which is at par with your GPU.
If your GPU is either too fast or too slow, it will result in a bottleneck. Also check if the game you have chosen is CPU intensive or GPU intensive as this also plays a major role.
On the other hand, you might want to either increase or decrease game resolution to prevent CPU bottlenecking your GPU.
If you lower overall game resolution and play games at lower than 1080p you will not face any type of bottlenecking or slowing down of game.
If you do not want to lower game resolution, then you should increase it to 1440p, as at this resolution, your GPU will have to process more graphical data at a much higher speed.
Your GPU will not be able to process this data as quickly as the CPU completes processing data. Since, your CPU has to do an equal amount of work be it at 1080p or 1440p.
3. CPU Overheating
Your CPU overheats either when your device is unable to cool down on its own, or when it produces a lot of heat way too quickly.
Regardless of cause, if your system continues overheating it will start shutting down randomly or completely crashing.
Initially, as it is your CPU overheating, it works slower than its usual speed while all other components including your GPU process data at their normal speeds.
This causes your CPU to bottleneck your GPU, as resistance is created between a very hot CPU and all other components.
In order to resolve your CPU overheating issue you need to determine why your CPU is overheating.
There are several causes for your CPU overheating including insufficient cooling, dirt accumulation, broken CPU cooler, worn out thermal paste and no/bad thermal paste.
If your CPU starts overheating as soon as you start your computer, you need to resolve this issue immediately, before it ends up permanently damaging your computer’s internal components or memory.
If overheating occurs gradually, you must refrain from gaming on such a computer as you will not be able to enjoy a suddenly interrupted gaming session.
Since, your overheated CPU might not be able to stay powered on for long, while causing your GPU to bottleneck.
You must start by listing down all general causes of CPU overheating, before diagnosing and rectifying it. Start by checking if your CPU’s internal and external cooling system are working properly.
If they are not working properly, you need to replace or repair fans or the entire system. Since, letting your system overheat regularly is very dangerous.
If it is not your system’s cooling issue, open up your CPU’s case and check for dust.
If it is a new PC (Personal Computer) dust might not be an issue, however if it is an older computer, you might want to clean it up thoroughly.
If thermal paste is degraded or not able to absorb heat, replace it.
Ensure your system is not stuck in a corner with no air flow, as it is one of the most common causes for overheating.
If it is not a physical or hardware issue, you must start checking for software issues. The reason why your CPU is overheating might also be why your CPU is bottlenecking your GPU.
4. Virus or Malware
If your computer is intruded by a malware (malicious software) it is said to be infected, since it stops functioning like a healthy computer. Malware is a software created for damaging any and all systems it is able to access.
While some malware only interrupts your system from working properly, some are used for spying on your activities, while some others are able to steal personal information or sensitive data.
There are several types of malwares, including viruses, spyware, adware, and worms. Each type of malware has a different function and capabilities.
If your computer has ever been connected to the internet, you could have unknowingly downloaded a virus on to your computer.
If your system is truly infected, it will show your CPU working at 100% load even when it is completely idle. This is dangerous as it leads to both overheating and bottlenecking.
Start by downloading a free or paid version of an antivirus software and start an entire system scan. Do not use any other applications actively, as your system might be forced to shut down before it completes scanning.
Allow your anti-malware software to run background checks anytime and also schedule scans in advance for weekends, especially, if your computer is being actively used during weekdays.
This way you do not need to put a scan or hold while working or let a scan slow down your work.
5. Windows Update
Windows offers regular updates to its users to ensure software and hardware compatibility as well as smooth functioning of Windows with other applications.
It also offers updates for all Microsoft programs. These updates contain updated security measures and feature enhancements.
If you have noticed that your computer has started making loud noises or is being forced to slow down, after installing and updating a new Windows update, you need to uninstall this update immediately.
Since, windows updates are often buggy and might end up in you causing your GPU to slow down due to CPU bottlenecking.
Do not download and update every time windows shows a new update is available as not all updates are free from bugs.
It is better to access Windows Update Settings in your computer and pause your system from searching for updates for up to five weeks.
By doing this you ensure you do not update for several weeks, during which even if a buggy update is released, you have not downloaded it and can wait till a corrected one is available.
In case you download a buggy update, you can easily roll back to its previous version.
In order to roll back an update and go to its previous version which was functioning properly click Windows+I key on your keyboard.
This opens Settings App in which you choose the “Update and security” option. A new screen opens on which you should see a “Recovery” tab.
Here, you will find a “Go back to an earlier build” section, under which you have to click on “Get started” button.
You cannot undo an update after 10 days, so take action within a week of installing any update. If it is past the 10-day period, you need to wait with this buggy update for the next update to be released.
Once you no longer have a buggy interface, your system will go back to operating optimally and bottlenecking will not occur.
6. Graphic Drivers
Graphics drivers are software programs required so that all applications and operating systems of your computer are given permission to utilize your computer’s graphics hardware.
If you enjoy gaming, you need to keep your graphic drivers up-to-date in order to get amazing graphics as a result.
These drivers are often updated, since applications as well as hardware keep upgrading/updating. You should download these updated drivers from time to time, as to maintain compatibility between software applications and hardware components.
Drivers of your computer’s motherboard, network and sound card do not need to be updated regularly, as they are often full of bugs.
These drivers on updating start causing problems to your CPU and other internal components.
They often force CPU to work at 100% usage resulting in overheating, CPU energy spike and CPU bottlenecking. So, if these applications are working fine, you need not update their drivers.
This same logic cannot be applied to GPU drivers, as these updates are regular and add major performance improvements on being installed. These improvements are especially useful for newer games.
In order to avoid your CPU bottlenecking your GPU, you should not download and update every time a driver is available for download.
Wait for a week or two after a new driver is available and then download and install it. You might want to create a recovery point before installing it. Since, it makes uninstalling a buggy driver easier.
Before learning how to update a driver, it is necessary to know where reliable drivers are available for downloading and how to uninstall and roll back to a driver’s previous version.
Previous versions of drivers are available through several websites for all Windows operating systems. After downloading a previous version, scan it for virus or malware before you begin installation.
In order to roll back to a previously functional driver from an updated buggy driver, you need to open Device Manager.
Once this window is open you have to choose a device for which you want to roll back a driver. Right-click on your selected device’s name and click on properties.
Once the property window is open, look under the driver tab, a button with a roll back driver is present. If you are sure you want to return to a previous version of a driver, click on it.
This device’s new driver will automatically be uninstalled and a fully functional previous version will be installed without any issues.
In case there is no option to roll back the driver, you can download a previous version and install it by accessing the Device manager window again.
7. CPU Bound Games
Some games require only a small part of your GPU’s processing power, since they are mostly dependent on your CPU’s processing power.
If you do not want to access a game’s settings and check whether it uses your GPU’s power or your CPU’s power, you can tell from observing certain factors when playing any game.
For instance, consider Demon Souls and GTA 5 (Grand Theft Auto 5), these two games to understand what game physics is, and how to determine how much CPU power is required by any game.
In GTA 5 random NPCs (Non-Player Characters) are found roaming about in this game’s universe, going about their own business.
Enemy characters in Demon Soul are similar in their actions as they have a fixed set of moves when they want to attack.
After getting defeated in GTA, NPCs’ bodies do not vanish, as this game mimics real-life physics. When you run over a person, they will get knocked down or be sent flying.
However, in Demon Souls, once enemy characters get defeated, they automatically vanish. Therefore, it does not follow real-life physics rules.
Since, this game does not require logic of real-life physics, CPU does not play a major role in interpreting its graphics. AI involvement in games increases CPU usage when playing these games.
Furthermore, with these CPU bound games, your CPU also has to direct data towards your GPU while instructing it about what should be displayed on your screen.
Since your CPU has to do a lot of work, it is quite likely that your CPU starts bottlenecking your GPU. For these games, your GPU is not the main processor, as most things are handled by your CPU.
Real-time strategy games, simulation games, complex environment games, and intelligent AI games are some types which need more resources from your CPU.
If you choose to play CPU intensive games, you can either choose to upgrade your CPU or overclock it.
If you have recently purchased your CPU or gaming PC, you should not consider upgrading to a better and faster model.
However, if your CPU is old and cannot keep up with all other components in your computer, you might consider upgrading to a newer, bigger and better model.
Overclocking is a process to make any component of your computer operate at higher speeds.
Your computer’s internal components have their own speeds; however, these speeds are measured through a system known as clock speed.
You can overclock multiple components of your computer, including your CPU, GPU and RAM.
If you are considering overclocking multiple components in your computer system, you need to be aware that overclocking often leads to an increased production of heat.
If you do not have a comprehensive cooling system available for your computer, you should not overclock multiple components.
Since, it will result in your system overheating and then crashing with multiple internal components melting.
Overclocking is a fairly complex procedure and should not be done if you do not have complete knowledge of it.
Overclocking your CPU is safe, especially if you know how to increase its processing speed just by a little.
Manufacturers always leave extra leg room for users to overclock their CPU if needed. By overclocking, you can play games at higher resolutions, without having to experience any sort of crash or lag.
You do not need to spend any extra money to overclock and once you have overclocked your CPU or GPU your computer will operate faster than it previously did.
However, if you want to improve your entire system’s speed, overclocking just one component is not enough. Only if you overclock multiple components can your system’s overall speed be improved.
If you know how to overclock and you are very careful while doing it, it is not very difficult.
You need to start by getting all information about your CPU and its motherboard and all other components you want to overclock.
Then you can find specific instructions about CPU overclocking and need to start downloading reliable overclocking software.
If you do not want to download any external software, you can overclock through your system’s BIOS (Basic Input/Output System) settings, which allows you to modify clock speeds for various components.
8. CPU Intensive Graphics
Based on any gaming application’s specifications, your CPU has to determine its frame rate. Following this even your GPU determines a frame rate considering resolution and game specs.
Your CPU bottlenecking does not have a major impact, if the maximum frame rate for your system is higher than the refresh rate of your monitor.
Furthermore, your CPU has to create visuals of shadow, volumetric cloud, water reflection, degree of expansion, dynamic lighting, particle shape, after treatment and field of view in a live game.
This task is fairly CPU intensive, therefore chances are your CPU will bottleneck your GPU, regardless of your CPU or GPU’s specs.
For CPU intensive graphics you need to modify settings of every game you intend to play on your computer.
Start by playing GPU graphics intensive games and start modifying all graphics related settings one by one.
Do not change any values by a lot suddenly, especially if you do not understand what change it will produce.
Once you understand what each and every setting does, start downloading games with more CPU intensive graphics.
9. Corrupted System Files
Corrupted files are damaged files that are unable to perform their general functions normally. All types of files can become corrupted, be they system files, program files or any documents.
You might have encountered a corrupted file at some point in time. However, these errors are mostly small and can be rectified immediately.
Files generally get corrupted when they are being saved onto your system. If your computer crashes or you lose power after a power surge, files do not get saved properly due to your computer turning off suddenly.
Sometimes, malware and viruses are also responsible for corrupting files. Damaged hardware or other memory devices can also create corrupted files, as these memory components cannot save them properly.
Each and every file has a fixed content and structure and in order for it to work properly, all information in a file needs to be arranged well.
In some damaged files, information gets stored in a different location than where you intended. Some corrupted files cannot be accessed at all while some others can be opened but cannot be read as all information in it is scrambled.
System files contain information important for running your system seamlessly. Therefore, if too many or important system files are corrupted, your CPU is unable to process properly, thereby bottlenecking your GPU.
Some corrupted files with minor damages can be corrected by rebooting your system. Once you restart your computer these files are able to save themselves properly, removing any corruption that had occurred previously.
Since, your computer also saves backup files in emergency, in case your system crashes or shuts down unexpectedly.
Corrupted system files that are not restored to their previous state immediately on rebooting, need to be restored through command prompt.
You need to use system file checker tools to determine which files are corrupted and then correct each file individually. Once files are repaired any problems your CPU is facing will no longer be an issue.
10. Parked CPU Core
In a multi-core processor, a parked core is a part of your CPU’s core that has been disabled by your operating system.
This is done to save power, as your CPU does not need this processing power at all times. This parked state sends a part of your CPU core to sleep, reducing its power usage to zero.
If it is functioning properly, you should not be able to notice any issue in parking and unparking your CPU’s cores.
However, core parking has its disadvantages as well, since it gives rise to severe bottlenecking issues.
With limited CPU processing power, CPU intensive tasks are bound to slow down your computer extremely.
You need to learn how to disable and enable your CPU core parking so that you can change this state according to your usage.
By disabling your CPU’s core parking, you will be able to use all of your CPU’s processing power.
This makes it easier for your CPU to process large amounts of data, so that it does not end up bottlenecking your GPU.
There are several free and paid tools which can be used to disable and enable your CPU’s core parking. By using these tools, this process can be carried out seamlessly.
If either of your processors are not working at similar speeds, it causes a bottleneck issue. To resolve this issue, you need to understand why does CPU bottleneck GPU in your computer.
Once you are able to narrow down to a few options from this list, seek assistance from experts to resolve this issue.