Why Does CPU Bottleneck at 1080p?

A CPU (Central Processing Unit) bottleneck occurs when your CPU becomes your computer system’s weakest link.

In most cases it restricts your GPU (Graphics Processing Unit) from performing at its maximum potential. It also slows down your entire computer system as a complete unit.

Does your computer slow down drastically when gaming at 1080p resolution, despite having a GPU with low workload? Read on to know why the CPU bottleneck at 1080p, since most graphics processing is handled by your GPU.

Reasons Why CPU Bottleneck at 1080p

Why Does CPU Bottleneck at 1080p

There is only one reason as to why the CPU bottleneck at 1080p. It is because gaming at 1080p resolution is less GPU intensive, and not more CPU intensive.

Since, CPU bottleneck occurs, it is often misunderstood that CPU prevents smooth gaming at and beyond 1080p.

Read on to know more and understand what actually causes your computer to slow down when gaming at 1080p.

CPU’s Role in Gaming

Your CPU is referred to as your computer’s brain, therefore just like a brain does, your CPU is tasked with simultaneously executing numerous processes.

It must be capable of processing several different types of operations like opening and working on spreadsheets, browsing online, editing videos and attending online meetings.

During gaming your CPU is responsible for processing data associated with the physics and logic of any game. It records how a user interacts with a game and then calculates what changes need to be made in game scenes.

This information is then relayed to your GPU. Based on your interactions, CPU interprets and communicates to your GPU how each object should look, behave or react.

To further elaborate, your CPU performs these actions while gaming:

  • AI and non-player characters – Inside a game, a complete universe exists where you, as an in-game character have to interact with fields, objects and enemy characters. These interactions need to be carried out according to a fixed set of rules and preset conditions.
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For instance, in a game based on sports, your character needs to put a ball through a goal post to be able to score.

Your CPU’s role is to execute these rules created by game developers. Hence, your CPU calculates your score based on where your ball lands.

Some conditions are flexible and change according to a player’s skill levels, and it is your CPU that enables these changes in your gaming experience.

  • Collision detection and hitboxes – In order to kill an enemy character on your first attempt, it is necessary to aim accurately. Your CPU decides based on calculations of distance and several other factors if a bullet will hit or where it will make contact with an enemy character’s body.

This is done through creation of 3D shapes known as hitboxes that are attached to a game’s characters.

This logic is also used for detecting collisions and if a punch will land in fighting games.

Hitboxes do not have a physical form i.e., they are invisible to a player, therefore, their creation and maintenance is completely dependent on your CPU.

GPU’s Role in Gaming

GPU plays a major role in gaming computers even though it is only assigned a few specific tasks that it is capable of performing well.

Your GPU’s most important role is processing graphical data through millions of calculations that are carried out parallelly.

Your CPU sends frame details to your GPU, which converts them into visual scenes and shapes which are then displayed on your system’s screen.

Bodies of water, patterns, reflections, glowing effects, shades and shapes are all generated though your GPU. If you have a high-end GPU, you can display a higher quality image with more details.

Your graphics card as well as CPU determine the resolution at which you can play a game. However, a GPU is of no use if it exists independently.

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A graphics card must be linked to a virtual memory, cooling fans and PCI express connectors. If these are not in a single unit with your GPU, you will need to install these in your CPU case separately.

RAM’s Role in Gaming

RAM (Random Access Memory) is a memory unit that contains any information temporarily to make it easier for data to be accessed by a processor.

If you are playing a game, it then stores game related information, making it easier for your CPU to search and gain access to this data.

Every core of your CPU can only run one cycle at a time, and in order to run a game and allow it to operate smoothly your CPU has to deal with millions of variables and perform trillions of operations using them.

Your RAM stores any and all information regarding these variables while they are being processed.

Gaming computers require a bigger RAM because you need it not only for running a game but all background processes that are active on your computer.

If you do not have enough space in RAM, it causes a blackout within games, as it is unable to pre-load a certain required part of a game’s universe.

If you do not have sufficient RAM your CPU will be forced to access game data from main memory.

This wastes clock cycles and causes lagging because your CPU is forced to work harder and for longer durations.

Moreover, during this time it is unable to execute game related tasks wasting even more time. Your gaming experience will be ruined as there will be several crashes if RAM is not sufficient.

Gaming at 1080p Resolution

Your CPU is doing the same amount of work regardless of whether you are gaming at 1080p, 1440p or 4K.

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On the other hand, your GPU is forced to do more work in less time when you are gaming at 1440p or 4K.

Your CPU bottlenecks because your GPU is not overloaded while processing at your CPU’s clock speed.

At higher resolutions your GPU is forced to process slowly, therefore making it responsible for bottlenecking.


You can resolve this issue in two ways. You can either upgrade to a better quality and faster CPU if possible. If you do not wish to invest in a new CPU anytime soon, you must start gaming at either higher resolutions or lower resolutions.

When you start gaming at 1440p or 4K your GPU has to slow down, bringing down its processing speed, thereby preventing CPU bottlenecking.

At lower resolutions both your CPU and GPU are not overloaded and therefore do not need to worry about processing speed and bottlenecking.


When you are gaming at 1080p, both your CPU and GPU have almost similar speeds, which causes CPU bottlenecking.

So, before you start gaming, check all components and whether they are compatible with your game.

Otherwise, you will have to choose lower resolutions for gaming since you now know why CPU bottlenecks at 1080p.

About Dominic Cooper

Dominic CooperDominic Cooper, a TTU graduate is a computer hardware expert. His only passion is to find out the nitty gritty of all computers. He loves to cook when he is not busy with writing, computer testing and research. He is not very fond of social media. Follow Him at Linkedin