To check if your CPU is working, first see if your computer turns on and shows the startup screen. If it does, open Task Manager (press Ctrl + Shift + Esc) and click the "Performance" tab to watch your CPU usage. A working CPU should show low usage when idle and higher usage when running programs. You can also download free tools like HWMonitor or Core Temp to check your CPU's temperature and make sure it's not overheating.

You don't need fancy tools or special training to check if your CPU is working. Your computer's processor, or CPU, is the brain that runs everything. When it stops working right, you might see crashes, freezes, or your computer might not turn on at all.

This guide shows you eight easy ways to test your CPU's health. You'll learn how to spot problems early and fix them before they get worse.

Quick CPU Problem Diagnosis

Use this table to figure out if your problem is caused by the CPU or something else. Look for your symptom and see what to test first.

Symptom CPU Likelihood Alternative Causes Quick Test Priority
Black screen, no startup Medium (30%) RAM, power supply, motherboard (70%) Try different RAM stick Critical
Crashes while gaming High (70%) Overheating, power supply (30%) Check CPU temps while playing High
Freezes or random restarts Medium (40%) RAM, drivers, power supply (60%) Check Event Viewer for errors Critical
Blue screen errors Medium (35%) RAM, drivers, hard drive (65%) Write down the error code High
Computer runs slow High (60%) Overheating, virus (40%) Run speed tests and compare Medium
CPU too hot (194°F / 90°C+) High (80%) Fan problems, bad airflow (20%) Check fan and thermal paste Critical
Slow to start up Low (15%) Hard drive, too many programs (85%) Check hard drive health first Low
Programs keep crashing Low (20%) RAM, software bugs (80%) Test RAM first Medium

1. Boot and Startup Checks

Listen for Beep Codes

When you turn on your computer, it runs a quick test called POST (Power-On Self-Test) before Windows loads. If your CPU has problems, your computer will often beep to tell you something is wrong.

Common CPU Beep Patterns

  • 1 Long + 2 Short Beeps: CPU not found or failed the startup test
  • 1 Long + 3 Short Beeps: CPU power or compatibility problem
  • Constant Short Beeps: CPU is too hot during startup
  • No Beeps + No Picture: CPU may have totally failed, or there's a power problem

Note: Different motherboards use different beep patterns. Check your motherboard's manual or search for your motherboard model and "beep codes" online.

What to Look For on the Startup Screen

If your computer shows a startup screen before Windows loads, check for these things:

  • CPU Speed: Should match what your CPU is supposed to run at
  • Number of Cores: All your CPU cores should show up
  • Temperature: Should be under 122°F (50°C) at startup
  • Error Messages: Look for "CPU Fan Error" or "CPU Over Temperature" warnings

Warning Signs During Startup:

  • Computer turns on but shows nothing on screen
  • Gets to BIOS but freezes before Windows loads
  • Keeps restarting over and over (boot loop)
  • Shows wrong CPU info or missing cores

2. Basic Performance Check

How Does Your Computer Feel?

The easiest way to check if your CPU is working is to pay attention to how your computer acts. If it's slow, freezes often, or crashes a lot, your CPU might be having trouble. Keep in mind that slow performance can also come from not having enough RAM or a failing hard drive. This is just a first step.

Using Task Manager

Task Manager in Windows lets you see how hard your CPU is working in real time. Here's how to use it:

  1. Open Task Manager: Press Ctrl + Shift + Esc or right-click the taskbar and pick "Task Manager."

  2. Check CPU Usage: Click the "Performance" tab to see a graph of CPU usage. When you're not doing much, usage should be low. It should go up when you run programs.

What Good CPU Usage Looks Like

Normal Behavior:

  • Doing nothing: 1-5%, sometimes jumping to 10-15%
  • Browsing or typing: 10-30%
  • Gaming or video editing: 60-90%
  • All cores working: The work should spread across all cores

Warning Signs:

  • Over 20% when idle: Could mean a virus or failing CPU
  • One core stuck at 100%: Might mean overheating or a broken core
  • Random jumps to 100%: Shows the CPU is unstable
  • Slow even under load: CPU isn't reaching its full speed

More Things to Check in Task Manager

For a closer look at your CPU's health, check these numbers in Task Manager:

  1. Base Speed vs Current Speed: Current speed should match or beat the base speed when working
  2. Logical Processors: Should show all the cores your CPU has
  3. Up Time: If this keeps resetting, your computer is crashing without you knowing
  4. Usage History: Look for weird patterns in the last 60 seconds

3. Check for Overheating

Why Temperature Matters

Overheating is one of the most common CPU problems. If your CPU gets too hot, it will slow itself down to avoid damage. This makes your whole computer feel sluggish.

How to Check CPU Temperature

You can use free programs like HWMonitor, Core Temp, or HWiNFO to check your CPU's temperature. Here's how:

  1. Download a monitoring tool: Pick one like HWMonitor and install it.

  2. Check the temperature: Open the program and look at the CPU temperature readings.

What You're Doing Safe Getting Hot Too Hot What to Do
Not much (idle) 86-113°F
(30-45°C)		 115-131°F
(46-55°C)		 133°F+
(56°C+)		 Check if fan is attached right
Gaming 122-158°F
(50-70°C)		 160-176°F
(71-80°C)		 178°F+
(81°C+)		 Get better cooling
Video editing 140-176°F
(60-80°C)		 178-194°F
(81-90°C)		 196°F+
(91°C+)		 Shut down right away
Stress testing 158-185°F
(70-85°C)		 187-203°F
(86-95°C)		 205°F+
(96°C+)		 Stop test, get better cooler
Overclocked 149-176°F
(65-80°C)		 178-190°F
(81-88°C)		 192°F+
(89°C+)		 Lower overclock settings

What to Do When It's Too Hot:

  • Above 194°F (90°C): Shut down right away to prevent damage
  • Above 203°F (95°C): The CPU will slow down or shut off by itself
  • Above 212°F (100°C): You could damage the CPU forever
  • Staying hot for a long time: This shortens your CPU's life

If your CPU keeps running above 194°F (90°C), turn off your computer right away. Fix your cooling before you cause lasting damage.

4. Run Diagnostic Tests

Windows Built-in Tools

Windows comes with tools that can help find CPU problems:

  1. Windows Memory Test: This is mainly for testing RAM, but it can also show if your CPU has trouble handling memory.

    • Press Windows + R, type mdsched.exe, and press Enter.

    • Choose to restart and check for problems.

  2. System File Checker (SFC): This checks for broken system files, which can sometimes happen because of a bad CPU.

    • Open Command Prompt as administrator.

    • Type sfc /scannow and press Enter.

CPU Testing Tools

Tool What It Does Best For How Hard Cost Main Features
Task Manager Watches CPU Quick look, beginners Easy Free Usage, speed, core count
HWMonitor Watches CPU Checking temperatures Easy Free Temps, power, fan speeds
CPU-Z Shows info CPU details Easy Free CPU specs, speed tests
Prime95 Stress test Finding hidden problems Medium Free Pushes CPU hard, finds errors
Cinebench Speed test Comparing performance Easy Free Gives you a score to compare
AIDA64 Everything Deep testing Medium Paid Tests all parts of your PC
Intel/AMD Tools Official tests Maker's own testing Medium Free Made by CPU makers
HWiNFO Watches CPU Detailed monitoring Hard Free Shows every sensor reading

How to Use Prime95:

  1. Download and install Prime95 from the official website.

  2. Pick a test type based on what you want to check:

    • Small FFTs: Makes the most heat, tests CPU cores only
    • Large FFTs: Tests how the CPU handles memory
    • Blend: Tests both CPU and RAM together

  3. Run the test for at least 15-30 minutes. For a full check, run it for 24 hours.

What Prime95 Results Mean

A Healthy CPU Will Show:

  • No Errors: Test finishes without any failures
  • Steady Temps: CPU stays under 185°F (85°C)
  • Steady Speed: CPU keeps its speed up during the test
  • All Cores Working: Every core shows activity in Task Manager

Signs of a Problem:

  • Errors: Messages like "Hardware failure detected" or wrong answers
  • Crashes: Blue screens, freezes, or sudden restarts
  • Speed Drops: CPU slows down a lot during the test
  • Uneven Performance: Some cores work much worse than others

Testing Newer CPUs

Modern CPUs need some extra testing steps:

  • Different Core Types: Intel 12th gen and newer have two kinds of cores that need separate checking
  • Speed Check: Make sure your CPU reaches its advertised speed
  • All Cores at Once: Test if all cores can run fast at the same time
  • Power Limits: Watch for the CPU slowing down because of power limits

5. Check BIOS/UEFI Settings

Make Sure Settings Are Right

Sometimes CPU problems come from wrong settings in the BIOS (the software that runs before Windows). Here's how to check:

  1. Open BIOS: Restart your computer and press the right key (usually Delete, F2, or Esc) before Windows loads.

  2. Check CPU Settings: Look for settings about CPU speed, voltage, and cooling. These should be set to default unless you're overclocking on purpose.

Update Your BIOS

Old BIOS software can cause CPU problems. Go to your motherboard maker's website to download the newest BIOS update. Follow their steps carefully to install it.

6. Physical Inspection

Look for Visible Damage

If you think your CPU might be broken, you can open up your computer and look at it. Make sure your computer is off and unplugged first.

  1. Take Off the CPU Cooler: Carefully remove the fan or water cooler from on top of the CPU.

  2. Look at the CPU and Socket: Check for bent pins (on older CPUs) or any visible damage to the CPU or the socket on the motherboard.

  3. Replace Thermal Paste: If everything looks okay, clean off the old thermal paste from the CPU and cooler. Put on a small, fresh layer of thermal paste, then put the cooler back on.

7. Check Windows Error Logs

Using Event Viewer

Windows keeps a record of hardware problems in a tool called Event Viewer. This can help you find clues about CPU issues.

  1. Open Event Viewer: Press Windows + X and choose "Event Viewer."

  2. Find Errors: Click on "Windows Logs" then "System" and look for any red error messages about the CPU.

Common CPU Error Messages:

  • WHEA-Logger errors: These usually mean a hardware problem, often with the CPU
  • Unexpected shutdown: Your computer turned off without warning
  • Blue Screen errors: Look for codes like MACHINE_CHECK_EXCEPTION
  • Program crashes: Apps that keep closing with memory errors

8. Common Problems and How to Fix Them

Problem 1: Computer Crashes While Gaming

Steps to Figure It Out:

  1. Check temperature while gaming: If it goes over 194°F (90°C), that's the problem
  2. Watch the CPU speed: Does it drop right before crashes?
  3. Try different games: Does it crash in all games or just one?
  4. Run Prime95: If Prime95 works fine but games crash, it's probably your graphics card

What's Usually Wrong:

  • 70% Heat Problems: Bad cooling or old thermal paste
  • 20% Power Supply: Not enough power or a failing power supply
  • 10% Old CPU: Damage from overclocking or just age

Problem 2: Computer Freezes or Restarts on Its Own

How to Find the Problem:

  1. Check Event Viewer first: Look for WHEA-Logger errors
  2. Test your RAM: RAM problems often look like CPU problems
  3. Try Safe Mode: If it works fine in Safe Mode, it's probably a software problem
  4. Run Prime95 overnight: Real CPU problems will show up within a few hours

What the Results Mean:

  • WHEA Errors Found: 90% chance it's the CPU or motherboard
  • RAM Test Fails: Replace the RAM before blaming the CPU
  • Safe Mode Works: It's a driver or software problem, not hardware
  • Prime95 Fails: Your CPU has a real problem

Problem 3: Computer Got Slower Over Time

Signs Your CPU Is Getting Old:

  • Slowly getting slower: A 5-10% drop over 5+ years is normal
  • Hotter than before: Same tasks making more heat than they used to
  • Less stable: Overclocks that used to work now cause crashes
  • Needs more power: You need higher voltages to keep the same speed

What to Do:

  1. Run speed tests and compare to what your CPU should do
  2. Clean out dust and put on new thermal paste
  3. Reset BIOS to default settings and test again
  4. If it's still 15%+ slower than normal, think about getting a new CPU

Should You Fix It or Replace It?

Fix It When:

  • Your CPU is under 3 years old and still has a warranty
  • The problem is clearly heat related (new cooler or thermal paste fixes it)
  • Your CPU cost over $300 to replace
  • You mainly use your computer for basic things

Replace It When:

  • Your CPU is over 5 years old with proven hardware failure
  • Multiple tests confirm your CPU isn't stable
  • You need more power than your current CPU can give
  • Fixing it would cost more than half of a new one

When to Get Professional Help

Ask a professional when: You're not comfortable testing hardware yourself, different tests give different answers, or the problem might be with other parts like the motherboard or power supply.

You can do it yourself when: You have some tech skills, the signs clearly point to a CPU problem, and you have access to testing tools.

Key Takeaways

  • Start with simple checks like watching if your computer boots and checking Task Manager
  • Use free tools like HWMonitor to check temperatures and Prime95 to stress test
  • Most CPU problems (about 70%) are actually heat problems that are easy to fix
  • Only about 10-20% of suspected CPU issues are real hardware failures
  • Always test RAM first since RAM problems often look like CPU problems
  • Check Event Viewer for WHEA errors, which are a strong sign of CPU trouble
  • Keep temperatures under 194°F (90°C) to protect your CPU