One CPU Core Hotter Than Others (Causes, Fixes)

 

If you overclock your CPU or frequently run CPU-intensive applications, you may have noticed abnormal heating inside the CPU.

Using temperature-monitoring apps can help you keep these temps in check and make sure nothing goes above the normal threshold.

However, as these apps show you the temperature of each CPU core, you may notice that not all cores have the same temperatures.

Is it normal, or should you be worried?

This article addresses everything you need to know about CPU core temperatures.

 

One CPU Core Hotter Than Others (Causes, Fixes)

 

1. Normal CPU Temps

 

An increase in CPU temps while the computer is in use or even idling is normal as heat is a normal by-product of computing processes.

However, there’s a certain limit to how hot your CPU cores can get because overheating can create serious problems for your PC or laptop.

When it comes to determining the normal CPU temperature range, there’s no one-size-fits-all answer since this range depends on many different factors, such as your computer’s make, components, and applications that you run at a given time.

For example, when your computer is running idle, it will have different temperatures than when you run CPU-intensive applications like games or video-editing tools.

While you should check your specific CPU brand’s normal temperature range, there’s an overall safe range to keep your CPU temps within it.

The best idling temperature for most CPUs is 40–45°C and 65–75°C while running essential apps.

However, the CPU can reach up to 90°C while playing games and running heavy programs.

In addition, laptops can run at higher temperatures because their components are more densely packed and have lower airflow.

 

When Should You Worry?

Although computers frequently run hot, especially under full load, there’s little to worry about.

High CPU temperatures don’t damage your CPU or motherboard because your computer has a failsafe mechanism that turns it off when it gets too hot.

That’s a helpful sign that tells you there’s something wrong with your PC components and you should take care of it.

If the computer turns off or restarts randomly or it keeps crashing under normal applications, you need to fix the issue.

That’s particularly urgent if you overclock and experience temperatures higher than 90°C since high temperatures can kill your CPU if the voltage also goes up.

 

2. Normal Core Temp Differences

 

It’s important to monitor the temperature of your CPU and each core to make sure everything is running smoothly and trouble-free.

However, as you check your CPU temps using third-party tools such as Core Temp, you may notice that each core has different temperature readings.

That’s an issue frequently reported by users who want to know if this difference in temperatures is normal or a cause for concern.

The main reason one core is running hotter than others is the way most applications work.

Most of the programs we run on computers are single-thread, meaning they only need one core to perform their tasks.

As a result, they occupy one core, which is typically the first core, and others run idle or perform heavier tasks.

One core is always working more than others.

This higher workload leads to higher temperatures, making the core different from others.

You may even notice that one of the other cores (and not necessarily the first one) is hotter because systems are different, and they may assign programs to different threads.

In addition, multi-core CPUs are designed so that one core is surrounded by others, making that core hotter than others due to lower airflow.

However, not any core temp difference is normal, and you should be worried when cores are hotter than others for more than 10 degrees.

In such cases, you should look for the possible causes of these high temperatures.

One of the primary culprits is thermal paste.

It could be old, not properly applied, or even not good quality.

The thermal paste has to be spread evenly over the heatsink, and even microscopic air bubbles under the thermal paste can cause temps to rise.

Make sure all parts are covered and the heatsink is installed correctly.

 

3. Reapply Thermal Paste

 

While there are different ways of applying thermal paste, one of the best ways, which is also the simplest, is the dot method.

You place a pea-sized dot of paste on the CPU and put the cooler on it.

Some people recommend using the line method, which means applying a line of paste on the CPU, but this can lead to less favorable results as it may not spread evenly.

Others prefer to go by the manual method, using a flat object to spread the paste because it gives you a smooth cover and helps you control the amount of paste.

However, it’s not recommended because it can create air bubbles.

Applying enough thermal paste can be tricky because today’s CPUs are bigger and may need more of that.

If you apply too little, you won’t get good results in cooling down the CPU, and applying too much will lead to messy spills.

In addition, if the thermal paste is conductive, you’ll get electric shorts and damage your motherboard.

Before applying thermal paste, clean the CPU and the heatsink with a microfiber cloth and ensure there’s no lint or old thermal paste left on the surfaces using isopropyl alcohol.

Placing the cooler is the trickiest part because you have to get it right on the first attempt.

If you don’t put it in the right place and direction, you’ll need to remove it, increasing the chances of getting air bubbles and an uneven spread.

Another thing to remember is that you should apply enough force while pressing the cooler down on the CPU.

The pressure should be small enough to avoid damaging the CPU and motherboard and big enough to get an even and smooth spread and prevent the cooler from sliding.

After applying the paste, inspect all components and ensure there’s no spill.

If you see thermal paste around the CPU, you’ve applied too much thermal paste.

In that case, you should clean off the paste and redo the entire process.

 

4. Delid The CPU

 

If reapplying thermal paste doesn’t work, you may need to take a more drastic measure, which can be scary as it’s delicate and needs a high skill level.

Delidding the CPU is a process used only by elite overlockers, but today’s delidding kits have made it much easier.

The CPU has a “lid” known as the Integrated Heat Spreader (IHS).

The heat sink on the CPU sends the heat from the CPU to the cooler.

Delidding means removing this lid and replacing thermal paste or liquid metal with more effective materials to better cool down the CPU cores than the stock thermal paste did.

Since the process is sensitive, make sure you know what you should do before and go over your CPU and thermal paste’s user manual to avoid possible mistakes.

Here’s a helpful video that shows you how to use the delidding kit components to delid your CPU.

 

5. Close Background Programs

 

While the CPU cores running hot may seem like a hardware-related issue, certain software programs can also lead to heating.

As mentioned, some CPU cores work harder than others, making them hotter.

You can lower their temperature by reducing their workload.

CPU-intensive programs running in the background can also cause CPU heating issues, including one core running hotter than others.

You could overlook the possibility of this simple cause because you may think the problem is more serious than that.

However, before trying other hardware-related methods, it’s recommended to close all background applications and monitor the temps to see if it changes anything.

Go to the Task Manager by pressing Alt + Ctrl + Del and check the Processes tab.

Go over the programs and see if you can close any of them, especially those taking up many CPU resources.

Now, run your temperature-monitoring program and see if it helps.

Another thing that can lead to CPU core heating is many temporary files containing useless data and junk files.

These files place a huge burden on the CPU cores and eat up lots of storage space.

Use an effective cleanup program to ensure your computer is junk-free.

 

6. Check For Faulty Sensors

 

Getting different temperature readings for different cores is generally a normal thing because of the way the CPU thermal sensors work.

Most of these sensors aren’t designed to give accurate readings, and their purpose is just to avoid thermal overload.

As a result, they don’t read temperatures below a certain value (around 50°C) and only give you a general indication of the CPU’s thermal state.

If the readings are different for up to 10°C, there’s nothing to worry about.

However, if you get large differences in readings and reapplying thermal paste and delidding doesn’t help eliminate the issue, you should ensure the CPU thermal sensors give you the correct readings.

That said, locating these sensors isn’t easy because every CPU manufacturer places them in a different location.

They may be on the CPU die or the interposer and you probably need to search and ask informed technicians to make sure your sensors are healthy.

 

7. Try General Cooling Methods

 

The temperature issues inside the CPU cores aren’t different from other thermal problems across the computer.

So, you can take all the measures for cooling down your PC and see if it helps.

Here’s what you can do:

 

A. Keep Your PC Clean

Dust buildup is one of the most important causes of overheating.

When dust accumulates on computer components, it can work as an insulator and prevent airflow inside the computer.

You need to regularly clean your PC, especially if it’s in a place with lots of dust.

Try cleaning your PC and see if the core temperature difference goes away.

Make sure to clean every nook and cranny, particularly the fans.

Be careful not to damage the sensitive components and use cotton swabs to clean tiny and hard-to-reach areas.

You could also use canned air to drive out the dust from the areas you can’t see.

By cleaning your PC, you’ll not only address the temperature issue, but you’ll also improve your PC’s performance and speed.

 

B. Improve Airflow

Although computers normally do a good job of keeping their components cool, you need to help your PC perform better.

One of the best things you can do is make sure there’s enough airflow going in and out of the PC.

Avoid putting your case inside cabinets or on soft surfaces like cushions or beds.

You want to make sure the air vents in different parts of the case aren’t blocked as it can severely affect the airflow.

However, you should avoid placing your computer in areas that get a lot of air, such as in front of the window or air-conditioner.

Plus, although you may think your laptop can be fine sitting on your lap, it’s not the optimal place for it because your legs can block airflow.

Place it on a desk, table, or a cooling pad with working fans.

If your computer is in a room with poor ventilation, you should make sure cool air can circulate easily around the computer by turning on the AC.

And never put your computer in a place where it gets sunlight for too long because it can heat the computer no matter how much airflow it has.

 

C. Check All The Fans

The fans in both desktop and laptop computers are essential in keeping the internal parts cool.

You should always make sure they’re operating normally and keep them dust-free.

Since fans have moving parts, they can wear down over time, reducing the fan’s efficiency in cooling down the innards.

Check the fans for any physical damage, loose wires, or broken blades, particularly for unusually loud noises.

If you can’t fix the issue, you should replace the fan.

Another thing to consider is the filters on the fans if there are any.

Ensure the filters are clean and not damaged, and replace them if they don’t work properly.

 

D. Stay Updated

Here’s another software-related issue that can cause one core to work harder and get hot.

When your programs are outdated, they don’t run as smoothly as they should and place a lot of burden on the CPU by eating up its resources.

Look for regular Windows updates and download them automatically or manually to ensure your system is updated and free of glitches.

Another factor that can cause programs to eat up CPU resources is malware and viruses.

Windows built-in defender normally does a good job of protecting your PC against viruses.

Still, you could install a reliable antimalware and antivirus tool to prevent your PC from getting infected and remove unwanted or harmful programs.

 

E. Change The CPU Cooler

If the CPU cooler has lost its efficiency in cooling down the system, you can replace it with more powerful ones.

Depending on your system specs and needs, you could go for air-cooling or liquid-cooling solutions.

Liquid-cooling solutions use a liquid, which is typically a glycol solution, to circulate the system and cool it down.

Some of these cooling solutions have light indicators that show you the thermal state of the CPU and the entire PC, but you need glass side panels on your case.

You can choose among different designs, including closed-loop and open-loop consisting of a heatsink, tubes, a radiator.

The best thing about these solutions is that they don’t require much maintenance as they’re sealed and very effective.

They dissipate heat much better than their air-cooling counterparts and are much quieter because they don’t have fans like those.

However, they’re more expensive and can be prone to leakage.

On the other hand, air-cooling units merely circulate the air inside the PC using a heatsink and fan that dissipate heat from the CPU to other parts and outside.

Most stock coolers are of this type, and you can replace them with more robust and effective options to improve cooling.

These units are simpler, so you can easily upgrade them without changing the tubing or the radiator.

In addition, you can use them on almost every system since liquid cooling solutions need specific designs that not every computer has.

However, these units can lead to higher temps inside the case because they dissipate heat from the CPU inside the case.