Why Does My PC Randomly Turn Off: 10 Reasons for Crashes

One of the most annoying problems you can face is your computer turning off randomly. You can be in the middle of some important office presentation or close to your objective in your favorite game when your PC shuts down without any warning.

There are a lot of reasons that may cause this to happen. The most common ones come as no surprise; overheating and power shortage. The components of your system are designed to shut the PC if there is a chance of damage.

So if you are asking yourself why does my PC randomly turn off, then this comprehensive guide should help you find the answer (fingers-crossed).

So Why Does My PC Randomly Turn Off?

There are several reasons why your PC can turn off randomly. I will cover each one in detail.

1. Overheating Components Including CPU, GPU, or PSU

One of the main culprits in random PC shutdowns is overheating. Three main parts, CPU, GPU and PSU, can overheat and turn the PC off randomly.

The CPU and the GPU have internal heat protection mechanisms: thermal throttling and complete shutdown. Both of these components can get hot for a few reasons

  • Insufficient or Bad thermal paste
  • Defective heatsink
  • Inadequate airflow
  • Accumulation of dust

Each of these problems can raise the operating temperature of your components.

There are several ways you can keep a tab on the temperature of your core components.

CPUs Often Suffer From Overheating Issues

CPU is perhaps the biggest culprit which often gets overheated due to bad airflow or bad thermal paste.

You can keep a check of its temperature using free to use third party software called called CoreTemp or RealTemp.

What is the Safe Idle CPU Temperature 2
RealTemp Showing the CPU Temperature

You can see above the minimum and maximum operating temperature of my CPU. These numbers are quite ideal.

These utilities also show you the distance to TJMax temperature. TJMax temperature is the temperature where your CPU will start to seriously throttle (reduce performance) or even shut your system down.

If your operating temperature crosses 90°C, then there is a high chance that an overheating CPU is causing your PC to shut down randomly.

GPU and PSU Can Also Overheat

In addition to the CPU, your PSU or if you have a dedicated graphics card with a bad air flow can both also be the culprit of your PC shutting down randomly.

Just like with CPU, you can keep a tab on GPU temperature using either of two free third party software GPU-Z or MSI Afterburner.

gpu z temperature main
GPU Z Showing GPU Temperature

PSU are a bit trickier. There is no software that you can use to monitor temperature of your PSU.

However, you can check physically. If you see that there is dust accumulated or if the PSU fan isn’t working, then there are high chances that the PSU is overheating.

Additionally, a slight touch of hand on the PSU can tell you whether it is exceedingly hot or not. Normally a PSU isn’t too hot to touch. Of course, make sure that your PC is disconnected from the wall socket before your touch the PSU with your bare hands. Even then, be very careful.

If you have a handheld IR Thermometer Gun, then you can use that to check the temperature.

Solution to Overheating

If you encounter any of these signs, start monitoring your CPU and GPU temperatures.

If you observe high temperatures, you can: perform thermal repasting, improve the airflow, and install a better cooling system!

If the insides of your desktop are neat and clean without any signs of dust accumulation and if the CPU or the GPU cooler fan are working effectively, then thermal paste degradation can be the culprit.

If the PC shuts down and doesn’t turn on immediately when you try afterwards, you should check the PSU for defects. It is also possible that the PSU is not giving out enough wattage for your system, and in this case, consider replacing it.

2. Did You Perform a Recent Overclock?

Did you perform a recent overclock of your CPU or GPU? If so not only can this raise the temperature of the components but also destabilize them.

Overclocking should not performed without proper guidance or without first providing adequate cooling to your system.

A bad overclock can damage your components beyond repair.


Bring your CPU and GPU back to default clocks. You can bring your CPU back to its default clock speed by resetting motherboard to factory default BIOS settings (remove the CMOS battery for 5 seconds and put it back in).

I explain this further in the following article:

Also Read:

3. Insufficient PSU / Power Surges

PSU comes in different wattage rating ranging from 300W all the way to 1200W and more.

If you have built a system that utilizes more power than the PSU can deliver, then that would naturally cause your PC to shut down.

In addition to that, the PSU has some safety mechanisms of its own against any anomalistic situations such as earth faults.

If there is any electrical surge or an earth fault detected, most PSU have built in function to turn the PC off. 

Finally, an old and worn out power supply unit can also cause your PC to shut down randomly.


If the issue is with an insufficient wattage supply, then it is time to upgrade your power supply unit. 

You can use free tools to calculate your power supply requirement. I am listing two below:

4. Malfunctioning or Not Properly Connected Hardware Components

Every PC part is integral for the PC to function properly. Elements like the motherboard, the RAMs, the disks, etc., must work simultaneously for the system to operate.

If a critical components fails, then either the system will start at all or your will often see a Blue Screen of Death.

Why Does My PC Randomly Turn Off
Blue Screen of Death (BSOD) – a common error caused by a malfunctioning hardware.

BSOD can be caused by various reasons, such as issues with the motherboard, improper connection of components, etc. One of the main culprits is the RAM.

The operating system relies heavily on the RAM to store temporary data before and after processing. If the RAM or the slot is defective or not inserted correctly into the slot, you can experience abrupt system crashes with the BSOD (blue screen of death).

Another main component is the disk. It does not matter what kind of disk you have the operating system on; SSD, HDD, or NVMe M.2, in case of a defect in the disk or the SATA cables connecting it to the motherboard or a faulty M.2 slot, the operating system will crash.

BSOD is also a hallmark error of a failing hard drive.

A not properly connected dedicated graphics can also cause your system to randomly turn off or not start at all.

A majority of the dedicated graphics cards not only have to be placed into an x16 slot on your motherboard, they also have to be connected with additional power supply cables.

graphics card connected
You have to make sure all the power connectors on the graphics card are connected to PCIe cables coming from the PSU.

Also Read: What are PCIe Cables Used For? 


If the you suspect the issue lies with the hard disk drive, then test your PC with another hard drive or test your hard drive in question on a different PC to see if the problem persists.

If you have two RAM sticks, take one out and test your PC with another.

Additionally, also check if the issue is not being caused by a defective port.

For that, try plugging your hard drive and your RAM sticks in a different slot. So for instance, if you have four RAM slots on your PC and two RAM sticks, try taking the RAM sticks out and putting them in the free slots.

If you have a dedicated graphics card, make sure it is plugged into the FIRST PCIe x16 slot on your motherboard and that all the power connected are connected to the PCIe cables.

Also Read: Does it Matter Which PCIe x16 slot I Use?

5. Viruses and Malware

Of course, one of the most dreaded issues that one can face.

A virus is one of the few causes of system failures and data loss. These small pieces of code can damage files, corrupt programs, erase data and steal information, to name a few. Malware is a specialized version of a virus designed to destroy data and steal information.

If you don’t have an anti-virus installed or if you have one but it is NOT upto date, then one of these might sneak into the system and wreak havoc.

The virus can infect integral operating system files, slowing the system down. Once the virus destroys some of the most crucial files of the operating system, the PC may even shut down randomly with or without a blue screen of death.


The only solution against viruses is to install an anti-virus and UPDATE it with the latest signatures.

Often people download and install an outdated version of an anti-virus software and never bother to update its signatures.

Since there are new viruses born almost everyday, it is important to that you keep your anti-virus software always upto date.

Once you have downloaded, installed and updated a trusted anti-virus software, scan the system thoroughly, and delete any suspicious files.

It is worth noting that prevention is better than cure. Hence, avoid any pirated data and third-party applications from unknown sources. Do not access new hard drives or flash drives without first running them through an anti virus scan.

There are many trusted anti-virus software such as McAfee, Norton, Kaspersky, Avast etc, however, even the Windows built in Virus And Threat Protection utility is more than sufficient for overall protection. 

6. A Dead CMOS Battery

One of the most common causes of a motherboard malfunctioning is a dead CMOS battery. 

Remove the CMOS battery for 5 second and then put it back in.

All motherboards have CMOS batteries. These batteries power the CMOS chip which stores the real time clock as well as the BIOS settings.

A dead CMOS battery means that you BIOS will not work and if your BIOS does not work, your motherboard can experience all kinds of issues including your PC randomly turning off.

If you often experience your PC not starting at all of one of the hardware malfunctioning randomly it is worth it to reset CMOS by removing the battery for 5 seconds and then putting it back in or by replacing it with a new one.

The CMOS battery is a CR2032 lithium coin cell battery.

Read in Detail: Why Do Motherboards Have Batteries?

7. Outdated Drivers

The device drivers are dedicated files that help the OS control a specific component. The manufacturer of components roll out updates every once in a while so that they work properly.

Windows has an automated system for detecting and installing any new driver updates through its Windows Update utility.

Outdated drivers for any module can cause it to crash or stop working altogether.

Additionally, any obsolete drivers can create vulnerabilities and system instability. If an integral component such as the GPU stops working, the system becomes unstable and shuts itself down to avoid damage.


A simple way of keeping the drivers updated is to run the automated Windows Update utility. This method is time efficient as you do not have to search out for each every driver for your component individually.

Windows updater
Windows Update Utility

The Windows Update Utility not only searches for newer drivers for all the connected components but also updates the Windows itself with newer patches and fixes.

You can access Windows Update utility by simply typing “Windows Update” in the Windows search bar.

8. Connected Peripherals Could Be Causing the Issue

For reasons unknown, there are some instances where the connected peripherals such as the mouse, keyboard, flash drives, external hard drivers, printers etc. can cause system crashes.

The issue could be driver related or your USB ports or the connected component could be malfunctioning.


Remove all the peripheral components and start your system. See if the problem persists. If not, then re-introduce each peripheral component one by one until you find the culprit.

9. Your OS has Become Corrupted Beyond Repair

If either accidentally or due to a malicious virus your OS has become corrupted beyond repair, then that can most certainly lead to crashes and your PC randomly turning off.


You will need to run Windows repair utility or you may have to format your drive and do a fresh Windows install.

10. You Have a Bad CPU or Motherboard

Finally, if you have tried everything and you have made sure that the rest of the critical components such as the GPU, RAM, Hard Drives and the PSU are functioning properly, there are no driver issues and your PC is clean from any viruses, then there is a possibility that your motherboard or your CPU may be dead.

This is one of the most dreaded issues you can face and the only solution here would be to either test your CPU on a different motherboard (with a compatible CPU socket) or test the motherboard with a different compatible CPU.

If the problem of PC randomly turning off persists, then this can help you verify whether the problem exists with the motherboard or the CPU.

I have written comprehensive guides on this topic which you can check:

Final Words

If you are wondering why does my PC randomly turn off then rest assured that you are not alone. This is a very common issue and in majority of the instances is caused by something as simple as an overheating CPU.

If you forgot to apply thermal paste, or if the CPU cooler isn’t working properly, that can lead to overheating, which in turn can shut your PC down randomly.

Besides overheating, a component not plugged in properly, accumulation of dust (particularly inside the RAM and PCIe slots), driver issues and viruses are other major culprits of PC randomly turning off.

In some instance, a bad RAM stick, dying Hard drive, or a GPU not properly connected can also cause this issue.

In the rarest of instances a dying CPU or a motherboard can cause your PC to turn off randomly and this, unfortunately, is the most dreaded issue which is very hard to fix.

Photo of author


Atif Qazi
Atif Qazi is the founder of PCGuide101 and an expert in the computer peripheral industry with over two decades of experience. He has worked as a consultant for major companies and has a deep understanding of the inner workings of computer peripherals. He has a degree in Electrical Engineering and has served as a product manager and technical consultant. He is passionate about testing and evaluating the latest products to provide readers with reliable information.

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