Hey there! Let's unpack what's going on here step by step.

First off, ntoskrnl.exe!ExTryQueueWorkItem isn't the "villain" here—it's a Windows kernel function that handles queuing background work items to system worker threads. So when you see it using CPU, it's just doing its job of processing some behind-the-scenes task that got kicked off.

Here are some common reasons you might see this kind of CPU spike:

• Temporary system maintenance tasks: Things like Windows Update background scans, system index rebuilding, or disk optimization (especially if you're using a mechanical HDD) often run in the background and can cause this kind of CPU blip that dies down after an hour or so.
• Driver-related background work: Outdated or buggy device drivers (think GPU, storage, or network drivers) might trigger kernel-level work items that keep this thread busy.
• Third-party software kernel components: Some antivirus tools, backup software, or system utilities use kernel-level hooks that can queue work items through this function.

To dig deeper if this becomes a recurring issue:

• In Process Explorer, when you have that thread selected, check the Stack tab (right next to Threads). This will show you the full call stack, which can point to the actual driver, service, or process that initiated the work item—this is the real clue to what's going on.
• You can also use the Windows Performance Monitor (perfmon) to track system worker thread activity, or run tasklist /svc in Command Prompt to see which services are tied to the System process, helping you spot any outliers.

If this only happens occasionally and drops off on its own, it's probably just a routine system task doing its thing. But if it's happening frequently or causing performance issues, updating your drivers, scanning for malware, or checking for problematic third-party software would be good next steps.

备注：内容来源于stack exchange，提问作者Snowy Diamond