There is a ghost in your Task Manager: a process called System Interrupts consuming 10, 20, or 30 percent of your CPU, and you cannot right-click it, cannot end it, cannot even see what it is. On Acer laptops this phantom CPU usage often appears after driver updates or Windows upgrades, and it makes the whole machine feel sluggish because that CPU time is stolen from everything else.

System Interrupts is not a program — it is the CPU time spent answering hardware interrupts, the signals your devices use to demand attention. High interrupts mean some piece of hardware (or its driver) is shouting at the CPU far too often. The fix is detective work: find the noisy device, fix or update its driver, and the ghost vanishes. For companion CPU mysteries, see System Interrupts on Windows 11 and our Windows 11 variant for Lenovo systems .

Why this happens

  • Faulty or outdated device drivers: A buggy driver can mishandle interrupts, causing the CPU to service the same device thousands of extra times per second.

  • Failing hardware: Dying hard drives, bad RAM, and flaky Wi-Fi cards generate error interrupts as they struggle, which shows up directly as System Interrupts CPU.

  • Problematic USB devices: Damaged USB drives, hubs, and peripherals are the most common external cause — one bad device can dominate interrupt traffic.

  • Network adapter interrupt storms: Wi-Fi and Ethernet drivers with interrupt moderation disabled or buggy firmware flood the CPU during network activity.

  • Storage controller issues: AHCI/SATA driver problems or a drive with reallocated sectors generate constant error-handling interrupts.

  • BIOS interrupt routing bugs: Firmware bugs in how interrupts are assigned to CPU cores, sometimes exposed by Windows feature updates.

  • High DPC latency from audio drivers: Bad audio drivers defer work (Deferred Procedure Calls) that Task Manager lumps near System Interrupts, causing audio crackle plus CPU usage.

How to fix it

Work through these in order — diagnose first, then act.

Fix 1: Confirm the scale and find patterns

Before touching drivers, characterize the problem so your fixes are targeted.

  1. Open Task Manager > Processes, enable the CPU column sort, and watch System Interrupts for two minutes — note whether it is constant or spiking.
  2. Test the triggers: does it spike when you plug in USB devices, during large file copies, on Wi-Fi activity, or when playing audio?
  3. Unplug ALL USB devices (mouse, drives, hubs, printers) and watch for five minutes — a dramatic drop implicates a USB device.
  4. Note whether it started after a specific event: Windows update, driver update, new hardware, or a drop/knock to the laptop.
  5. Download Microsoft’s Process Explorer and enable the Interrupts display for a more precise reading than Task Manager provides.

Fix 2: Identify the noisy driver with LatencyMon

LatencyMon shows exactly which driver is causing interrupt/DPC storms — turning guesswork into evidence.

  1. Download LatencyMon (free, from Resplendence Software’s official site) and run it as administrator.
  2. Click the play button and let it monitor for 5-10 minutes during normal use.
  3. Check the Drivers tab sorted by DPC count and ISR count — the top driver is your prime suspect (common offenders: network, audio, storage drivers).
  4. Google the exact driver filename (e.g., ndis.sys, storahci.sys, or a vendor .sys) to identify which device it belongs to.
  5. Write down the culprit driver name — the next fixes target it specifically.

Fix 3: Update the culprit driver

Most interrupt storms are driver bugs fixed in later versions.

  1. Open Device Manager, find the device matching the LatencyMon culprit (network adapter, audio, storage controller).
  2. Right-click > Update driver > Search automatically first — quick but often insufficient.
  3. For the real fix, download the latest driver from Acer’s support site for your exact model, or from the chip maker: Intel for Intel Wi-Fi/chipset, or your Wi-Fi card vendor’s site.
  4. Install, restart, and re-run LatencyMon for 10 minutes to confirm the driver’s interrupt counts dropped.
  5. If Windows Update keeps reinstalling the bad driver, use Show or Hide Updates troubleshooter or Group Policy to block that specific driver version.

Fix 4: Test hardware suspects one by one

When drivers check out, the hardware itself may be generating error interrupts.

  1. Test USB devices individually: plug each one in alone and watch System Interrupts for two minutes per device.
  2. Check drive health: run wmic diskdrive get status and check CrystalDiskInfo for reallocated sectors or warnings.
  3. Test RAM with Windows Memory Diagnostic (search it in Start, restart when prompted) — bad RAM causes machine-check interrupts.
  4. Disable the Wi-Fi adapter in Device Manager temporarily and test on Ethernet (or vice versa) to isolate network hardware.
  5. If a specific device is confirmed bad, replace it — no driver update fixes hardware generating spurious interrupts.

Fix 5: Update the BIOS

Acer regularly fixes interrupt routing and power-management firmware bugs in BIOS updates.

  1. Find your exact model and current BIOS version: run msinfo32 and note BIOS Version/Date.
  2. Visit Acer’s support site, enter your serial number, and compare with the latest BIOS for your model.
  3. Read the BIOS changelog — look for mentions of system stability, interrupt, or power management fixes.
  4. Run the BIOS update on AC power with the battery charged above 50%; close all apps and do not touch the laptop during the flash.
  5. After the update, re-run LatencyMon — firmware-level interrupt fixes show up immediately as lower ISR counts.

Fix 6: Tune interrupt-heavy settings

A few settings reduce interrupt load even when the underlying driver is merely mediocre rather than broken.

  1. For network adapters: Device Manager > network adapter > Properties > Advanced — enable Interrupt Moderation if present.
  2. In the same Advanced tab, try disabling energy-saving features like Energy Efficient Ethernet as a test (they can cause interrupt bursts).
  3. For audio crackle plus interrupts: Settings > System > Sound > device properties and lower the sample rate, or update the audio driver.
  4. Disable unused devices in Device Manager (old Bluetooth radios, unused network adapters) — every active device generates some interrupts.
  5. In Power Options > Advanced, set PCI Express > Link State Power Management to Off as a test; aggressive link power states can cause interrupt storms on some Acer boards.

Fix 7: Clean-install the driver stack as a last resort

When a driver is corrupt rather than merely old, only a full removal and reinstall clears it.

  1. In Device Manager, right-click the suspect device > Uninstall device and check Attempt to remove the driver for this device.
  2. Restart — Windows installs a generic driver; test interrupt levels with the generic driver as a baseline.
  3. Install the manufacturer’s latest driver fresh on top of the clean state.
  4. If the problem survives a clean driver install and a BIOS update, run DISM /Online /Cleanup-Image /RestoreHealth and sfc /scannow to rule out OS corruption.
  5. Persistent high interrupts after all software fixes, especially with a drive or RAM warning in diagnostics, means failing hardware — back up your data and arrange a repair. Microsoft’s Windows support hub documents the built-in diagnostic tools used above.

Closing

System Interrupts is the CPU’s way of telling you a device will not stop shouting. On Acer laptops the shouting usually comes from a buggy network, audio, or storage driver — LatencyMon names the culprit in minutes, and a proper driver update or BIOS flash silences it. Work the evidence, not the guesses, and the phantom CPU usage disappears.

Frequently asked questions

What is the System Interrupts process in Task Manager?
System Interrupts is not a real process — it is Task Manager’s way of reporting CPU time spent handling hardware interrupts, the signals devices use to get the CPU’s attention. Every device from your Wi-Fi card to your USB ports generates interrupts, and the CPU must pause to service each one. A healthy system spends under 2% of CPU on interrupts; when the figure climbs past 10% and stays there, some device is interrupting far too often.
Is high System Interrupts CPU a virus?
No. Malware does not show up as System Interrupts — it shows up as its own suspicious processes. High interrupt CPU is a hardware or driver problem: a device misbehaving at the electrical level, a buggy driver mishandling interrupts, or a failing component spamming the CPU with requests. If your antivirus scans are clean and System Interrupts is the top CPU consumer, stop looking for malware and start looking at drivers and hardware instead.
Why do System Interrupts spike when I plug in a USB device?
USB devices generate interrupts for every data transfer, and a faulty device — a dying external drive, a cheap USB hub, a damaged cable — can generate thousands of spurious interrupts per second. The pattern is diagnostic gold: if System Interrupts jumps the moment you connect a specific device and drops when you unplug it, you have found your culprit. Try the device on another computer to confirm whether the device or your laptop’s USB port is at fault.
Can outdated BIOS cause high System Interrupts?
Yes, particularly on Acer laptops. The BIOS/UEFI firmware configures how hardware interrupts are routed, and bugs in interrupt routing (APIC configuration, power management states) are regularly fixed in BIOS updates. If high System Interrupts appeared after a Windows feature update and driver fixes do nothing, a BIOS update from Acer is a strong next step. Always update BIOS on AC power with the battery charged, and never interrupt the process.