What a CPU (Processor) Does When it Goes Bad or Is Failing

A blown-up electrolytic capacitor vent with dried electrolyte residue. This component's failure was due to overheating from abnormal DC current conduction.
A blown-up electrolytic capacitor vent with dried electrolyte residue. This component's failure was due to overheating from abnormal DC current conduction. | Source

The CPU is the brains of your computer. When your computer's CPU is getting older, is used to do functions for which it wasn't intended, or overheats due to poor power flow, it could fail completely.

Here's how to determine what's causing your CPU to fail and what the problem means. We will discuss how to use a basic approach to determine the problem as well as some other issues that may be involved as well.

This process can be a long and expensive process of elimination. Hopefully this article will help you get to the source and save you time and money in the end.

Bad Capacitors

A bad capacitor on a motherboard.
A bad capacitor on a motherboard.

Common Reasons Why a CPU Goes Bad

The most common reasons for CPU's to go bad are simple:
1. Age. Every machine has its limits. A computer that is five years old or older is considered to be in its grace years. They can just give up.
2. Heat. Overheating CPU's lead to a dead CPU. This can happen when room temperature is often above 80 degrees Fahrenheit and if the computer has an ineffective cooling mechanism inside.
3. Overclocking or Stress. Not all CPU's are created equal. Don't make a dual-core do what an eight-core is intended for. Overclocking has its place, but be careful to be realistic. Also, if a game says it needs a certain minimum to run, don't run it on an under-clocked CPU. The same goes for software for video or photo editing. If you want to over-stress your processor this way, by all means go for it, but otherwise upgrade.
4. Electrical Power Surge. Whether it was the power supply going bad or lightning, any high voltage spike can render a CPU useless. Be sure to have a surge protector and a battery backup attached to your computer to help prevent this sort of thing from happening.

The Simple Approach to Finding the Problem

Processors made by AMD, Advanced Micro Devices. AMD is the second largest manufacturer of microprocessors, smaller only than Intel.
Processors made by AMD, Advanced Micro Devices. AMD is the second largest manufacturer of microprocessors, smaller only than Intel.

Uninterruptible Power Supply

APC Battery Backup & Surge Protector (BE550G) - 550VA 8-outlet Uninterruptible Power Supply (UPS)
APC Battery Backup & Surge Protector (BE550G) - 550VA 8-outlet Uninterruptible Power Supply (UPS)

This article's first photo shows what can happen to a CPU capacitor when the power flow isn't consistent. Protect your machine by attaching it to an uninterruptible power supply. If there is a power spike, your computer will be protected.


Common Failure Symptoms

CPU's often simply burn out. To determine that is your problem, consult this list of common processor failure symptoms:

  • Computer turns on, no beeps, no screen. Does not POST (Power-On Self Test)
  • Computer turns on, fans run at highest speeds, still no POST, and operating system not loading.
  • Computer powers on, but turns off immediately.
  • In Windows (or any other OS), screen freezes after being on for a few minutes. In some cases, the screen may freeze during the load screen of the OS (a.k.a. the Windows logo screen).
  • System halt errors (famously known as blue screen of death) that calls out the processor as an issue.

Eliminating False Positives

There are other components besides the CPU that can create the above symptoms. This can lead your diagnostics astray.

Below are some simple things to look for that can cause the same symptoms. Once they are eliminated, you may have a bad processor. Otherwise, you have found the real source of the problem.

Check List

1. Heat. Next to dust, heat is the number one processor killer. Most CPUs run from 30 degrees Celsius to 50 Celsius. If your machine is not cooling well, then there is an issue. CPUs above 70 degrees Celsius are in the danger zone. Between 80-85 Celsius is the melting point. Check the heat-sink in your computer and make sure it is clear of dust and obstructions. Make sure the fan on the heat-sink is moving smoothly (3,000 rpm is average +/-.) If the fan and heat-sink are fine, then the thermal compound may be old and dried up. Replace the thermal compound. The thermal compound should be applied evenly, about one mil thick. (Note: System temperatures can be viewed within the system BIOS or by using a utility to monitor the CPU settings.) If you are going to replace the thermal compound, I strongly recommend Arctic Silver 5.
2. Capacitors. Look for any bulging or leaking capacitors on the motherboard near the CPU or memory areas. If there are any bulging or leaking capacitors, this creates voltage irregularities, thus system errors.
3. Power Supply. Much like bad capacitors, bad power supplies can create all kinds of strange voltage and amperage irregularities. Check the power supply with a tester to see if it is in good health.
4. Video Card. If your system has a dedicated video card, check its capacitors and fan as well. Video cards can freeze a system, in the same way a CPU can. They can also keep a computer from POSTing.

Video Card Bad Capacitors

Bad capacitors on a video card.
Bad capacitors on a video card.

After Checking Everything

If all the above checks out well, then you are looking at a bad CPU and maybe motherboard. This is especially true if all the fans and lights are on but "nobody is home" when the computer is turned on.

At this point, the only way to clearly diagnose the CPU/motherboard is to get a working CPU and replace it. If all goes well, then the CPU was bad. Otherwise, it was the motherboard or both.

Did your CPU Die? How?

How Did your CPU Die?

  • Power surge from outside the computer (lightning, etc.)
  • Power supply failed, caused damage to CPU
  • Overheated due to dust or bad thermal compound
  • Wasn't CPU after all, it was another component
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© 2013 Ryan Hutzel

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Comments 15 comments

ambe 3 hours ago

Hi. I have a laptop. Everytime I use it , it shutdown after several minutes. Can you help pls?

newbie 4 weeks ago

thanks man

ryansccs profile image

ryansccs 2 months ago from Greencaslte, PA Author

@Jenna Rose, try connecting an external USB keyboard to the laptop and see if you get the same results. If it works, your issues are simply your keyboard is failing. I have seen this before in the years of repairing systems.

Jenna Rose 2 months ago

My Samsung dual core laptop purchased end 2010 is lagging (typing, scrolling and page loading) even after installing a new hard drive I noticed no changes or improvement. I have removed my battery to see if it would make a difference but according to what I am reading here it seems to be something other than hard drive or processor. It happens even when I'm offline ? :O

kelvin musyoka 4 months ago

like your job

Andre 7 months ago

Noticed a similar failure on two different Core 2 Duos.

Symptoms: random data corruption and BSOD's, it appears one core goes bad and somehow dumps the data in one register into another.

I wrongly assumed that the problem was the RAM, turns out not to be the case.

Bryan 7 months ago

very helpful, thank you very much.

ryansccs profile image

ryansccs 14 months ago from Greencaslte, PA Author

@Ray Y, likely a virus is the reason, or at least a good start to investigate.

Ray Y 14 months ago

PC boots up fine, the Intel Core i7 CPU jumps to all 8 running at a consistent 100%. Cam opem apps and work but CPU overheat protection kicks in at 70 degrees and computer shuts down. Why does CPU after a few years instantly jump to 100%? Corsair good quality power supply, rated to be well able to provide for all components. In BIOS all other temperatures besides CPU are cool to safely warm including additional thermal monitors around inside case. Cannot be just thermal paste since CPU gradually climbs up in heat over time. The issue is the CPU instantly going 100% on all cylinders. System has been able to run multiple virtual machines with sufficient RAM. Any comments?

TTGReviews profile image

TTGReviews 23 months ago

I've lost several CPUs trying to overclock; however, it's much easier to get right nowadays.

ryansccs profile image

ryansccs 2 years ago from Greencaslte, PA Author

There really is no solid way to test our motherboard if it does not pass POST (beeps.) You would need to test the CPU in a known working motherboard to determine if it is a CPU issue.

edvhin 2 years ago

sir i have a problem.. i test video card, vga/dvi cable,ram,hdd, its fine

but when i boot up..sometimes the fan of cpu spinning on and off. and no signal appear on the monitor. so what will i do is.. i checked and unplug all. and then plug it again. ows.. success.. it boot up.. again but after 5 minutes it automatically shut down and it will appear a blue screen.. again and again. i thought it was a psu but still fine. the problem here is etheir motherboard or cpu was damage. the symtoms of cpu going to bad is the same with the mobo. my question is hiw can i test the motherboard if its ok or bad?

Dave 2 years ago

Nice and helpful article .. thanks

Ardon Davies 3 years ago

I visit this web site for my college research it was very helpful for me I got everything I was looking for on my class assignment of failing processors systems.

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jabelufiroz 3 years ago from India

Nice article on Failing Central Processing Unit. Voted up.

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