Unplug USB devices one at a time and watch the CPU, update audio, network, chipset and graphics drivers, disable audio enhancements, turn off Fast Startup, and update the BIOS. Use LatencyMon to identify the exact driver.

Why this happens

Hardware sends interrupts to the CPU when it needs attention: a key press, network packet or audio buffer. Normally this takes under 1–2% CPU. A faulty device, failing USB peripheral or buggy driver can generate thousands of extra interrupts, which shows up as a large System interrupts figure.

Because it’s hardware-driven, the fastest diagnosis is to remove devices and update the drivers most often involved: USB controllers, audio, network and storage.

How it shows up

  • Task Manager shows “System interrupts” using 10–100% CPU.
  • Audio crackles, mouse lag, stuttering.
  • Usage drops when a particular device is unplugged.

What causes it

  • Faulty USB device, hub or cable.
  • Outdated audio, network, chipset or storage drivers.
  • Audio enhancements or exclusive mode problems.
  • BIOS bugs or failing hardware.

How to fix it, step by step

  1. Unplug USB devicesDisconnect USB devices one at a time (including receivers and hubs), watching Task Manager for a drop.
  2. Update driversInstall the latest chipset, audio, network and graphics drivers from the manufacturer.
  3. Disable audio enhancementsSettings → System → Sound → your output → Audio enhancements: Off.
  4. Use LatencyMonRun the free LatencyMon tool; its Drivers tab shows which driver has the highest interrupt (ISR/DPC) time.
  5. Turn off Fast Startup and update BIOSDisable Fast Startup in Power Options, and install the latest BIOS.
  6. Disable devices to testIn Device Manager, temporarily disable suspect devices (e.g. internal Wi-Fi, webcam, card reader) to see if usage drops.
Check it's fixed: System interrupts stays under ~2% CPU at idle.

Keeping it from coming back

Use good-quality USB hubs and cables and keep chipset drivers and BIOS updated.