"System Interrupts" process using high CPU
Matthew Harrington 
I installed Windows 10 in UEFI mode and have experienced high CPU usage due to a process called "System Interrupts". It takes up 18-30% of my CPU all the time. I've tried installing it on my SSD, on my main HDD, and the problem still persists. I booted into Safe Mode, and tried using Windows 8.1, and the problem still persists. Should I switch to non-UEFI version to solve the problem?
21 Answer
System interrupts appears as a Windows process in your Task Manager, but it’s not really a process. Rather, it sums up the CPU usage of all interrupts that happen on a lower system level.
Interrupts can originate from software or hardware, including the processor itself.
An interrupt alerts the processor to a high-priority condition requiring the interruption of the current code the processor is executing. The processor responds by suspending its current activities, saving its state, and executing a function called an interrupt handler to deal with the event.
Once the interrupt handler task is completed, the processor resumes where it was interrupted.
There are two utilities you might be able to use to identify your problem and check the DPC
This older utility still mostly works on Windows 10. DPC stands for Deferred Procedure Call and is related to system interrupts. When the interrupt handler needs to defer a lower priority task until later, it calls DPC.
DPC Latency Checker was designed to analyze whether your system can properly handle real-time audio or video streaming by checking the latency of kernel-mode device drivers, but it also reveals issues.
This tool requires no installation. Launch it and let it work. If it shows red bars, this means that you have too high DPC counts.
This a latency monitor that can count DPC per driver.
To find the driver with the highest DPC count, download, install and launch LatencyMon. Press the Start/Play button (green arrow), wait some time, then switch to theDrivers tab, and click twice on the DPC column to sort the driver files by DPC count in descending order. Drivers with a high DPC count potentially cause a high number of interruptions.
This might look like this:
Ignore the first item, which is the tool itself. You should then examine the other high entries. You may google for the Driver File name to find out what device it serves. You may also disconnect such devices (if you can) to verify if they are really the cause.
You may indicate here which drivers you have or have not managed to identify which have a high DPC count. You could look for drivers for these devices on the manufacturer's website.
