Windows 10 bugs are likely to blame for this issue. There are a few ways to fix this. You can restart your computer or terminate the inactive process using Task Manager. If none of these methods work and Task Manager still shows only one core, reinstall Windows 10 and hard reset.

Despite having several cores, Task Manager may show only one core active. If the previous application you ran utilized a different core, Task Manager will continue to show it using that core after it re-sorts. Follow these steps to restore Task Manager access to all cores.

What Indicates Only One Core Showing in Task Manager

If task management shows only one core, your computer’s processor may be malfunctioning. If this happens, run a diagnostic on the machine to find out what’s wrong. In Windows 10, go to Settings > Update & Security > Troubleshoots and select Run the latest version of Troubleshooter to use the built-in troubleshooter.

Reasons for Task Manager Showing One Core

Here are some probable reasons why your Task Manager displays only one core, as well as solutions to the problem.

1. Overclocking the CPU

Overclocking can be a complex, but also very straightforward operation. It all comes down to these steps: 

• Determine a stable CPU voltage. 
• Determine a stable CPU clock frequency. 
• Run Prime95 and check the temperatures to ensure stability. 
• Congratulations if Prime95 completes without faults. Your processor has been successfully overclocked.

2. Virus Attacked

If you only see one core in the task manager, it could be a symptom of malware on your computer. This could be the result of a virus or spyware that was installed on your system. The steps below will show you how to determine the truth and eliminate the virus

• Select Start, then put regedit into the search bar and click Enter.
• Navigate to HKEY LOCAL MACHINE > SOFTWARE > Microsoft > Windows NT > CurrentVersion > Image File Execution Options in Registry Editor.
• Check all of the files mentioned under this title to check if any have weird letters without an extension; if so, this could be a malware danger.

3. The CPU Fan Is Not Functioning Properly

Thermal paste blockage or drying out might cause CPU fans to malfunction. Thermal paste can’t transmit heat from the CPU to the heatsink and back into the air when it’s clogged. Overheating might damage your computer’s hardware. If the thermal paste dries up, the same thing will happen.

4. Windows 10 Has a Problem

It’s possible your graphics card driver is broken. If so, reinstall your operating system to fix it. You can also try updating your graphics card driver. If you’re still having issues, contact your computer or graphics card manufacturer.

5. Malware or Ransomware Has Infected Your System

If your system is infected with malware or ransomware, the task manager will likely show only one core. You may also notice that your computer is running slowly and that your internet connection has stopped. If this is the case, immediately back up your data and seek professional help.

Simple Solutions to Only One Core Showing in Task Manager

Here are several quick fixes to consider in this situation.

Fix 1: Check the Device Status

Check System Information to discover if the Processor is running at 100%. If this is the case, your CPU may be malfunctioning.

Next, look for any yellow or red flags in Device Manager. If you detect anything wrong, uninstall it and restart your computer.

Fix 2: Make Sure You’re Using Windows 10 1607 or Later

If you’re using Windows 10 and only see one core in Task Manager, it’s possible that your computer is employing power management. Navigate to Control Panel and select Power Options. Click on Change settings that are presently unavailable and then on Choose what the power buttons do.

Under Related Settings, you must tick both boxes: Hibernate after enabling quick startup (recommended). Then press the Save Changes button. When you open Task Manager again, you should see all four of your cores available.

Fix 3: Start the Performance Troubleshooter

If Task Manager shows one core, your machine may be broken. Test Performance Troubleshooter. Start by searching for Performance Troubleshooter on Windows 10. Follow the on-screen instructions to finish. Troubleshooting can take 5–15 minutes, depending on the number of issues. The system restarts automatically when you finish.

Fix 4: Install the Most Recent GPU Drivers

One of the most prevalent reasons for this problem is the usage of old or corrupt GPU drivers. To resolve this issue, update your GPU drivers as follows:

• From your desktop, right-click and select NVIDIA Control Panel or AMD Radeon Settings.
• On the left side of the window, select Driver Version.
• Select Check for Updates to install any available graphics card updates.
• When prompted, restart your computer to complete the installation.

Fix 5: Check the Power Settings

• Press Win+R to launch the Windows Run box, then enter Control (without the quotations). This brings up the Control Panel.
• Select Power Options, then under Related Settings, select Change Plan Settings for your active power plan.
• Choose Change the advanced power settings to 99% and then to Processor power management- Maximum processor state. Then click the Apply button.
• Exit the Control Panel and reboot your computer.

Fix 6: Turn Off Turbo Boost

During intense loads, Intel Turbo Boost technology allows for more CPU cores to be active. However, if Task Management only shows one core, Turbo Boost is most likely activated. To disable this option, perform the following steps:

• Go to Start and enter Power Options. From the findings, select Change plan settings. 
• Select Change advanced power settings from the menu. 
• Double-click Processor power management in the right-hand pane. 
• Increase the processor’s maximum state to 100%. 
• Press the Apply button.

Last Words

Task Managers may show one core for numerous reasons. Other programs may be using or inactive on other cores. The operating system may not recognize other cores. If this is a new issue, it is best to restart the computer and see if the problem persists. If the issue persists, see a computer expert.