How To Fix a Computer That Randomly Restarts

Modern computers have working stability that is much higher than the stability of the computers in the late ‘90s – early ‘00s. Nonetheless, nasty bugs sometimes make us frenzy, because they make the working process problematic. Besides the BSODs and malicious software, there is a thing that is much harder to understand – constant PC rebooting.

Why do PCs reboot without any reason?

There are plenty of reasons for PC unpredictable restarting. All of them are pretty serious, so solving them is likely an essential thing to save your computer and your data. To understand which problem is yours, you need to check each possible case, until you find one that is yours. To make the process structured, we will divide it into two parts – hardware and software-related checks.

Hardware-related problems

These things are the most dangerous ones. While the software issues usually do not affect file safety, hardware ones do. It is essential to figure out properly what the problem is and deal with it as soon as possible.

Power issues

One of the most widespread reasons for the sudden PC rebooting is power supply problems. It may be damaged, worn or just overloaded, but the effect is simple: some of your hardware parts do not receive enough power and then shut down, causing the PC rebooting. To figure out, if that is the case, use online services that allow you to calculate the power your computer consumes1. Then, you can just compare the number with your power supply max power emit. If the power supply can emit less power than your PC can consume, the problem is right there.

Broken power supply

Damage or wear of the power supply is harder to detect. In fact, only the serious damage of this PC part can be seen: outbalanced cooling fan, damaged cables and so on. It may be even worse, but in worse cases, you will not be able to start your computer at all. If you managed to do all next checkups and did not fix the problem, bring your power supply to the service.


The era of “cold” CPUs passed long ago. Now, only ARM-based chips that are used in smartphones and some other mobile devices are able to be cooled passively – without any fans, heat sinks, and so on. Computer hardware, on the other hand, can heat up significantly. Even more problems appear when you use a compact system unit, or a laptop. Both of them tend to have problems with heat sinking, especially when the hardware is working at high temperatures. You may check the current temperature of your hardware elements in Task Manager, as well as in third-party apps that can check the data hardware sensors. Normal temperature for CPU/GPU while running something heavy is ~70-80°C2. Lower is better, higher is not.

High CPU temperature
High CPU temperature can be spectated in a special utility

The reasons for overheating are different. Generally, if you did not install any new hardware, but discovered that your computer is overheating, it is a good idea to open the system unit and clean the detail up from the dust. It is a perfect habit to clean your computer at least once a quarter – just like washing your car. If you have changed your hardware, and the problem appeared, it seems that you will need to update your heat sinks. In some cases, you may even need a water cooling system.


That is a particular case which, however, touches both overheat and power issues. Overclocking is a process of increasing the CPU clock rate by increasing the bus multiplier. Most modern Intel processors do not offer such an ability – only ones that have K/KF letters in their index. AMD CPUs, on the other hand, can easily be clocked regardless of the model (at least, the vast majority of them). Not only the processor may be overclocked – GPU power can also be increased in such a way. But the negative effects are pretty much the same

FX CPU overclocked
This CPU was overclocked on about 30%. That may be enough to cause overheating and power shortages

Overclocking causes an increased power consumption and increased heating. The correlation between power use and clock rates is not linear: it is rather similar to parabolic graphs. Generated heat, however, is strictly related to the power usage. Nevertheless, an overclocked PC may suffer from both power issues and overheating. If so, try to decrease the clock rate – it will likely help you.

Disk issues

It is a rare source of a problem, but it still can appear, especially if you use HDD. In contrast to SSD, HDD can be dying slowly, getting one bad sector after another. One time, the bad sector can appear at the cell where some crucial system info is stored. When the system tries to get this info and fails, it may just trigger a rebooting. However, a much more common case in that situation for modern computers is BSOD.

Victoria HDD
The interface of Victoria tool. Green and orange tiles on the image say about the disk damage.

To prevent any issues with your HDD, check it with disk scanning tools. Victoria is one I would recommend to you: it is the oldest one, and showed itself perfectly through the last 20 years. The scanning process takes about 1.5-2 hours, and it is recommended not to use your computer during the scan. You will be able to see the problematic sectors on your disk, together with ones that are already bad or inaccessible.

Software-related reasons for PC rebooting

In a positive case, the reason for constantly rebooting a PC is related to the software you have on your computer. Most of these reasons cannot even be called a problem – it is just an unregulated need. However, there is still a way to fix that.

System updates

Operating systems nowadays receive updates each week. Windows has a regular updating schedule: at least 2 minor updates during the month and a cumulative update every quarter. Moreover, there are half-yearly patches that possibly bring new functionality to the OS. Sometimes, when you do not update your PC for a long period of time or have reinstalled the Windows from an old image, you may get into a situation where the system tries to install all possible updates. And most of these patches require rebooting.

Windows update rebooting PC

It is recommended to just wait until the system receives all the required updates. They are released not just to annoy you. Important bug fixes, closing the security breaches, new functions – all these things are vital. But when you need to access your PC here and now, and have no time to wait – just schedule the installation of the update, or temporarily disable them.

Third-party software updates or other actions

Same to the OS, third-party programs may also require the reboot of your PC. Oftentimes, they offer the user the choice – to reboot now or later. But there are rare cases when they have a timer on rebooting, or does not give you a choice at all. In that case, try to install all updates and control the installation manually – just to be sure that you don’t miss any windows3.

Program installation rebooting PC
The program asks for the PC rebooting to complete the installation.

Malware-related issues

Rarely, malicious programs may cause your computer to reboot. In some cases, these reboots are caused by the extremely high CPU/GPU load. Such a load may happen when you are infected with coin miner viruses. But most of the viruses that are spread nowadays do not have such side effects. They are concentrating on making money on you, this or other way. And making such disruptions in this “farming” is not the best solution.

I hope that this guide will help you to resolve the problem you have. For sure, I cannot describe all the particular cases that may cause the PC rebooting problem. But this guide represents all common cases, which will likely solve the problem you have.

  1. Check out how much power your PC can consume.
  2. Detailed information on the normal CPU temperature during different actions.
  3. Read how to keep your PC in a perfect state.

By Polina Lisovskaya

I have been working as a marketing manager for many years and I like to look for interesting topics for you

View all of Polina Lisovskaya's posts.

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