The Signs and Symptoms of a Bad CPU (How to spot a bad CPU)

My PC is dead. She won’t boot, she won’t talk to me, and the fans that fill her with life’s breath refuse to spin. 

All signs and symptoms point toward a bad CPU.  

But that got me thinking…

What exactly are the signs and symptoms of a failing computer processor? Instead of just ripping out my CPU in anger and frustration, I pulled out my phone, put on my Sherlock cap, and started an investigation.

And my findings are presented in this article.

In this article:

  • We’ll quickly look at what is a CPU and why it’s important
  • We’ll investigate the most common signs and symptoms of a dying CPU
  • Take a look at the most common reasons for a CPU dying and how to avoid them
  • We’ll look at how to fix a bad CPU set up that can lead to failure. 
  • Then we’ll wrap it up with what you should do next.

Ok, now you know what we’ll be talking about let’s get stuck in. 

A Very Brief Intro: What Is A CPU and Why They Are Vital To Your PC.

One vital part of your computer system is your CPU. It’s the brain of the computer.

The CPU controls all other actions that take place inside your computer. 

If the CPU fails, your computer will refuse to work. Until you get your CPU fixed or replaced, all your computer’s good parts are just a heap of metal. 

For more information on CPUs and their importance within a PC check on the CPU Wikipedia Page here.

Signs and Symptoms Of A Dying CPU 

When your computer’s CPU gets older, is overlooked, or overheats due to poor power flow, it could fail completely. 

But before you conclude that your CPU’s a goner, you should rule out other possible hardware failures first.

Let’s look at the main symptoms of a bad CPU one-by-one…

System Boot Up Issues

When you turn on your computer and nothing happens (not even beeps that indicate a POST test is running), there are several possible reasons why your machine won’t run.

Common causes that mess up a computer’s boot sequence include the following: 

  • Incorrectly installed software
  • A failed update
  • Driver corruption
  • Registry corruption
  • Virus and malware infections
  • The system didn’t shut down properly after an abrupt power outage. 

So how do you fix it?

Instead of spending time trying to find out the problem, Windows 10 includes the Startup Repair feature designed to quickly fix the most common issues that may be preventing your computer from loading correctly.

To use the Startup Repair feature, you’ll need to access the Advanced startup settings. 

If your computer isn’t loading, just follow these steps to access the recovery environment:

  • Turn on your PC.
  • Press the power button as soon as the Windows logo appears on your screen like the one below. Doing so will interrupt the machine’s boot sequence. Repeat this step 2 more times.
  • After the third interruption, you’ll now have access to the Advanced Startup environment and the Startup Repair tool.

If the Startup Repair doesn’t work and you’ve ruled out all the things I’ve said above, you’re now looking at two possible culprits: 

  1. You have an issue with your motherboard
  2. You have yourself a processor failure

The only way to test either of which is to do a visual inspection and/or test the parts with other components. 

Your Computer Crashes or Shuts Down Immediately

You wait for several agonizing minutes for your computer to boot up, and once it does, it’s lagging.

Normally, this can be resolved by simply clearing your browser cache, or by deleting some programs from your computer startup process. You can even defragment your hard drive to clear up more space. 

However, if you’ve done all that and your machine still responds sluggishly, this may be an indication of a bad CPU.

A more obvious sign is as soon as you turn on your PC, it immediately shuts down. 

There are several reasons why your computer might shut down without warning. One is the sudden temperature spike as soon as you turn on your PC.

When starting a PC, the CPU is flooded with high voltage electricity (relatively speaking). A byproduct of this voltage is large amounts of heat. Your CPU has a safeguard against excessive heat so if the heat isn’t managed correctly with a good cooling solution the CPU will shut itself down.

The problem is, this safeguard isn’t always enough, and repeated high heat events can lead to your CPU dying.  

If you’re using a new computer, or the motherboard was recently replaced, make sure that the thermal compound between your CPU and cooling solution is properly applied to the processor. If the heat is not properly transferred from the CPU to the heat sink, it can overheat almost immediately and damage your processor.

Also, check that the fan on your CPU cooler is working. 

If you’re using a water cooler for your CPU. Check that the water pump is actually ticking over. You should be able to hear the pump on top of the CPU if it’s working. 

Another CPU destroying culprit is a defective power supply. Typical failure of a PC power supply is often noticed as a burning smell just before the computer shuts down. 

While minor power supply failures may cause inadequate electrical power to vital components, major failures can literally melt your CPU! 

Fortunately, PSUs aren’t that expensive. You can buy a decent one from Corsair for as little as $50. But before you do, dump some cash on a PSU, be sure it has enough power to run your graphics card. But as a general rule of thumb, 650 Watt Power Supplies should be enough to run any single card set up. 

The Blue Screen of Death

We hate it. We all dread it: The Blue Screen of Death! 

BSoDs are fatal system error messages that abruptly pop on your computer screen out of the blue. 

The whole point of a BSoD is to protect your PC. When Windows senses a serious issue that could cause real harm to your hardware, it stops everything completely. The result? The infamous Blue Screen of Death. 

A BSoD can be caused either by poorly written device drivers or malfunctioning hardware such as faulty memory, power supply issues, overheating of components, or hardware running beyond its specification limits.

It’s also a symptom of a deteriorating processor. 

What can you do about it?

The first step to troubleshooting a BSoD is to ask yourself what you did just before the device stopped working.

Did you update a driver, updated Windows, or install a new program? If so, that may be what’s causing the BSoD. 

To resolve this, you need to undo the changes you’ve made prior to the blue screen. Depending on what it was that changed, some solutions might include:

  • Uninstalling apps that aren’t required during the installation of a Windows 10 upgrade
  • Disconnecting any unnecessary hardware
  • Erasing everything and starting from scratch with a fresh copy of Windows 10 performing a clean installation
  • Uninstalling system updates, drivers and apps if the error appears after installing a device driver
  • Fixing the blue screen with System Restore
  • Starting your computer in Safe mode to uninstall updates, drivers, and undo system changes that may be causing blue screen errors 

However, if none of these methods work, it could indicate a CPU problem. 


This is perhaps the easiest to spot in our list of CPU failure symptoms.

A sure sign that your computer is overheating is when your fan is always running at maximum speed. Another is your computer’s reduced performance since CPUs tend to cut back its clock speed to compensate for the heat pressure.

But if your system heats up too much it may trigger a fail-safe and shut down to prevent hardware damage. 

How can you prevent your system from overheating?

Keeping your device cool is not hard at all. Here are a few points to remember:

  • Always keep your computer clean. Dust and grime get sucked into the computer case by the cooling fans and builds up over time, insulating your computer and increasing heat. Open up your tower once every few months, and give it a good dusting
  • Give it space. Look around your computer and see if there isn’t any object that is obstructing the airflow. If there is, then immediately remove whatever’s blocking the air from passing to the computer
  • Clean your fans using a canned duster or cleaner. Frequent cleaning of fans keeps them producing optimum airflow 

Most Common Reasons Why Your Processor is Failing 


Understand that every machine has its limits, just as our bodies do. 

The average lifespan of a computer is typically three to five years, depending on how it’s used. Properly maintained computers, on the other hand, will last far longer than this.

Overclocking or Stress

While overclocking your processor can speed up your computer, there are far more reasons why you should not overclock your CPU. 

For one, it might damage your hardware. Faster clock speeds increase heat. And if you increase heat too much, it can overwhelm a cooling solution almost instantly. Do this too many times, and your CPU will eventually die. 

Electrical Power Surges

Power outages don’t really cause direct harm to your computer hardware. However, power outages can sometimes be accompanied by power surges which can cause real damage to hardware components including your CPU. 

As far as power surges and spikes are concerned, your biggest worry should be lightning that carries several million volts of electricity. 

Pumping that sort of power through your CPU is like trying to fit the flow of Niagara Falls through a straw!

Electronic devices aren’t designed to withstand that kind of energy, and before you know it, you’ve got yourself a fried circuit and a charred processor.  

But you can easily protect yourself: Buy yourself a surge protector and you’re protected against everything from blown breakers to storm-force lightning.  


Modern processors now have built-in thermal protection designed for situations where the system experiences a sudden increase in temperature. This either slows down the CPU or stops it completely if the computer overheats. 

With that said, even if your CPU isn’t throttling, constantly allowing your system to overheat will drastically shorten your PC’s lifespan.

Fix this by buying a high-quality cooling solution such as a water cooler or a high-quality fan assisted cooler

How To Fix a Bad CPU

If your CPU has actually died, then there is no way to fix it. 

The only thing you can do is maintain your CPU to ensure it gets to live a long life. 

Here are some ways you should maintain your CPU

Regulate Your Processor’s Temperature

It’s important to establish a “baseline” temperature for the processor when it is idle and under load. Why? Because it’s impossible to recognize abnormally high temperatures if you don’t know what the normal temperature should be.

Core Temp is a simple, lightweight app that runs in your system tray and monitors the temperature of your CPU without cluttering it up with other stuff. 

When you run it, it will appear as an icon or series of icons in your system tray showing the temperature of your CPU (one for each of its cores). 

Keep Your PC Clean

Give your computer a bit of dusting once every few months to avoid the accumulation of dust and grime, and maintain free airflow. 

If your case has an inlet air filter, then make it a habit to check if the filter is clean. 

Invest in Good CPU Coolers

CPU coolers vary greatly inefficiency.

While the CPU cooler that came with your retail-boxed processor can do the job fairly well, switching it for a quality aftermarket CPU cooler can reduce CPU temperatures by 10° C or more!

You can use either a high-quality CPU water cooler or stick with a traditional, but tried and tested, fan assisted cooler

Upgrade Your Computer Case

The processor itself is already a major heat source, which is why you might want to consider upgrading your computer chassis. 

A Good family of CPU cases that offers fantastic airflow and heat distribution are cube cases. They are usually cube-shaped, hence the name, and shorter, squatter and wider than traditional cases. 

But because of their shape, they usually come with a single very large fan on the front of them to pump vast quantities of clean cool air inside. 

Take a look at the fantastic – I know, because I use this case for my gaming rig – Thermaltake Core V21 here. Once you go cube, you’ll never go back…


A computer’s processor is almost always the absolute last component of a system that will die. The only thing that will outlast a CPU is the case itself.

A bad CPU is not only an expensive doorstop, but it stops you from getting any work done as well. Thankfully, a ‘dying’ processor is bound to exhibit signs of failure which you can troubleshoot.

When you have a defective CPU, you might encounter problems with booting up your device, your computer crashing or shutting down immediately, overheating, or the dreaded blue screen of death. 

How long your processor lasts really depends on you. Just give your PC a much needed TLC, and you won’t have to buy a new one for the next 10 years!

What Next?

My CPU has died, what should I do? 

If you’re sure your CPU is dead. It’s time to upgrade. You could buy an old CPU to fit your old motherboard, but you have no idea how the failing CPU affected the motherboard. You are better of buying new. I’d go for an AMD Ryzen CPU and a motherboard to support it

My CPU is ok! But my motherboard is dead, what should I do? 

If you’re absolutely sure your motherboard has died on you, then you need to buy a new one. There’s no way of fixing them. You can either buy a motherboard to fit your current CPU or you can buy a newer motherboard and upgrade everything in one go. Personally, I’d recommend taking a look at AMD Ryzen CPU motherboard and Ram bundles as you never know if a failed motherboard has affected your CPU in some way. But that’s just me. 

I think my Power Unite is the problem, what should I do?

You need to buy yourself a new PSU for your computer. Most SIngle graphics card PC needs no more than 650 Watts of power. So take a look at this great PSU from Corsair.

Beth Morris

Beth's love of gaming started when she first played Frogger on her Tiny PC. Since then she's developed a love for FPSs, a need for speed playing Forza, and a hunger to find dragon's eggs in Spyro! When she's not gaming she's either cooking, reading, or spinning around in her car!

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