Understanding and Resolving Persistent 100% CPU Usage on a Newly Built PC
Introduction
Experiencing unexpectedly high CPU usage can be both frustrating and concerning, especially after investing in a new custom-built PC. This article aims to guide users through diagnosing and resolving this common issue, based on a real-world example of a recently assembled system. We will cover potential causes, troubleshooting steps, and solutions to help restore your system’s optimal performance.
Case Overview
The user built a mid-range gaming PC approximately a week ago, featuring a Ryzen 7 5800XT processor paired with a Wraith Prism cooler. Initially, the system operated normally. However, over the past few days, the CPU usage began fluctuating abnormally, often reaching 100%, without any apparent reason. Attempts to troubleshoot included offline scans, malware removal tools like Malwarebytes, Safe Mode operations, and even performing a complete system reset via cloud download.
Despite these efforts, after resetting, the CPU usage remains at 100% from the moment Windows loads, causing system fans to ramp up and preventing task management tools from reducing the load. The user reports that even disconnecting from the internet does not alleviate the issue, and attempts to close processes in Task Manager are ineffective.
Common Causes of Constant High CPU Usage
- Background Processes and Services
- Malware or Unauthorized Software
- Driver Issues or Hardware Conflicts
- System or Windows Updates
- Faulty or Overheating Hardware
- BIOS Configuration Problems
Troubleshooting and Solutions
- Verify Hardware Temperature and Cooling
- Use hardware monitoring tools like HWMonitor or Core Temp to check CPU temperatures.
- Ensure the Wraith Prism cooler is properly installed and functioning.
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Clean dust from fans and heatsinks; improve airflow if necessary.
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Check for Malicious Software
- Run comprehensive malware scans using multiple reputable tools.
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Consider offline scanners or bootable antivirus rescue disks for thorough cleaning.
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Examine Running Processes
- Open Task Manager and identify any unfamiliar or resource-intensive processes.
- Use Process Explorer for advanced analysis.
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End suspicious processes cautiously and monitor system response.
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Update Drivers and BIOS
- Ensure all device drivers, especially chipset and graphics drivers, are up to date.
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Check the motherboard manufacturer’s website for BIOS updates and apply them carefully.
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Investigate Windows Settings
- Disable any startup programs or background services not essential.
- Check Windows power settings; set the power plan to “High Performance
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