PC ComponentsCooling

Why Do CPUs Generate Heat?

Thermal Paste

CPUs constantly send information through electrical signals, which in turn generate heat. While it is normal for your CPU to generate heat, it can be problematic if the heat gets too high. But why do CPUs generate heat? 

Quick Answer

Generally, the electricity passing through the CPU is what generates the heat. But the amount of heat a CPU produces can be influenced by several factors like the thermal design power, the number of transistors, clock speed or frequency, CPU bus speed, an integrated graphics heat sink, fan, CPU size, and other factors.  

If your CPU generates too much heat, you should troubleshoot it to confirm where the problem is coming from and find a way to bring it back to normal temperature.

The normal idle temperature of a CPU ranges between 40oC and 50oC (104 oF and 122 oF). And based on real-time computing and processing demands, the CPU temperature can rise to 80oC (176 oF). But when the CPU is stressed or overworking, the CPU can be as hot as 100oC (212oF).

Keep reading to learn some of the reasons CPUs generate heat. 

Why CPUs Generate Heat 

A CPU can perform numerous tasks simultaneously due to tons of electric current input and outputs through gates, semiconductors, and transistors. As the current passes through the computer’s hardware, including the CPU, it heats all these parts. The CPU specification is one of the most significant reasons the CPU generates so much heat. 

Below are a few key things that impact the heat generated by a CPU. 

Reason #1: Thermal Design Power of the CPU

The thermal design power of a CPU is the amount of power a CPU consumes under the maximum theoretical load. The higher the TDP, the higher the CPU’s potential to generate heat.

For example, the Intel 8086 CPU released in 1978 has a TDP of 1 W and generates less heat compared to modern CPUs like the Intel Core i7-8086K released in 2018, which has a TDP of 95W. Note that the leap from a 1 W to a 95 W is huge.

To protect the CPU, modern manufacturers integrated a thermal throttle that shuts down the CPU to cool down when the temperature goes as high as about 90oC (194oF) to 100oC (212oF)

Reason #2: Number of Transistors 

CPUs are made up of multiple transistors that help to regulate the flow of electricity through the CPU logic gates. The more transistors on a CPU, the faster it can compute data, but the more heat the CPU generates in the process.

For example, the obsolete Intel 8086 processors had 29,000 transistors and generated less heat than the more modern Intel Core i7-8086K, which has around 3 billion transistors

Reason #3: Clock Speed/Frequency 

The clock speed or frequency of a CPU is essentially the measure of the number of cycles it executes per second. The higher the frequency, the faster the CPU can compute data.

But technically, the cycle is a pulse synchronized by an internal oscillator. Hence, a 1.0 GHz CPU will generate less heat than a 4.0 GHz CPU. A high clock speed is directly dependent on the electrical current drawn by the CPU and another hardware component. And when there is more electric current flowing through the CPU, more heat will be generated. 

Reason #4: CPU Bus Speed 

Another factor that influences the speed of a CPU and how much heat it generates is the bus speed. The bus speed is typically the speed of the front side bus that connects the CPU to the Northbridge. The Northbridge is where the CPU reaches the memory controller.

Usually, the FSB speed ranges from 66 MHz to over a thousand MHz.  If the CPU has a high bus speed, it can go back and forth to the Northbridge to send and receive data, but it also means that more current is flowing through, generating heat in the process. 

Reason #5: Integrated Graphics 

Some computers come with a dedicated graphics card, while others have an onboard graphics processor embedded in the CPU. An integrated graphics card means that the hardware doesn’t use a separate memory bank for video and graphics processes, but the system memory is shared with the CPU. And as you may already know, GPUs are notorious for generating a lot of heat. But in comparison, an integrated graphics card does not generate as much heat as a dedicated graphics card. 

Reason #6: Overclocking or Turbo Boost 

Most CPUs today support overclocking and turbo-boosting, but doing so can increase the amount of heat the CPU generates. The reason people overclock a CPU is often to enhance the processing and computing speed. But they are breaching its TDP and using more electricity, generating more heat.

When overclocking and turbo-boosting a CPU is not done correctly, it could damage the CPU, especially when the CPU is not built to handle such stress as some CPUs are built with a thermal throttle to lower the clock speed to preserve their lifespan.  

Reason #7: CPU Size, Fan, or Heatsink

Furthermore, the size of the CPU can also influence the amount of heat it generates. A large CPU has a big surface area to distribute the heat, thus dispersing it more efficiently than a smaller CPU. And a large CPU with a well-built heatsink and fan will further increase how much heat is dispersed from the CPU compared to a smaller one. This explains why despite the higher performance of some desktop CPUs, they tend to perform better than a laptop in terms of heat generation.  

Keep in Mind

While the CPU generates heat, the ambient temperature of the room where the CPU is can also influence the temperature of the CPU.


As you can see from this article, there are several reasons CPUs generate heat. If you notice your CPU is generating too much heat, there are several ways you can diagnose the problem. Most often, running troubleshooting software will give you a clearer insight into what is going on in your CPU. And when you can detect the cause, you should fix it to cool down your CPU. If the problem is a little bit out of your scope, feel free to take it to a technician for further assistance. 

Leave a Comment

Your email address will not be published. Required fields are marked *