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It is basically not possible for me to unmount and disconnect my externall HDD because as soon as I plug it in, Windows Explorer uses massive disk usage (>100 MB/s) for about 10 minutes, and then the System process uses 20-40% CPU usage to do... something... and this persists until I shut down the computer and unplug the external HDD. I recently reinstalled Windows 11 because of this, to no avail. Any ideas how I might go about figuring out what the hell Windows 11 is doing with my external HDD? I caught it copy-pasting a huge file (>40 GB) from it to my Windows partition as a temp file (maximum storage of about 250 GB). Is anyone else experiencing this? For reference, my computer is a Dell Precision 5540.

EDIT 1

it looks like only drive C: has any idexing activity, but I rebuilt the index anyway. Twice, actually (reboots in between)

Does Windows 11 index directories not explicitly specified by you?

the 'System' process initializes this thread even when no drive is inserted now apparently, and it will last indefinitely, using between 15-30% CPU while it does... whatever it is that it is doing. I've let it go for 72 hrs several times.

EDIT 2

Excellent suggestion to use Sysinternals Process Explorer to probe the 'System' process. You can see that 'System' is not using disk I/O so much right now, but is using enough CPU to make my fans blow at max speed indefinitely.

Double-clicking on 'System' lets me see which thread is responsible for the high CPU, and its start address is ntoskrnl.exe!KeInitializeApc+0x4c0

Now the real fun begins. Any idea why ntoskrnl.exe might be using so much system resources indefinitely? It seems like other users have this problem with similar computer models. My fans are permanently on maximum speed 10-30 minutes after I turn the computer on because of this parasitic process.

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  • Probably indexing. Perhaps you should let it finish.
    – ChanganAuto
    Commented Jan 22 at 16:59
  • That was my thought as well. The size of the copy is more than many index files. Do you have a process resident on the external drive causing this?
    – anon
    Commented Jan 22 at 17:03
  • I also assumed it was indexing, but I disabled indexing on all drives, and rebooted the computer. The behavior didn't change. I always tried to just let it run, but it stops disk usage after a while and just has this infinite process running. I guess that could still be indexing, but I let it run for 48 hrs before. I could try it again and see. What do you mean by a process resident on the external drive?
    – cst_ramirez
    Commented Jan 23 at 23:04

1 Answer 1

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Windows both checks a drive for malware with Defender and indexes the drive if you let it. Since a large file is being generated, it's likely Search Indexer slowing down access.

  • Either let Search finish indexing, or

  • Press Windows, type indexing and select Indexing Options. In the Advanced dialog, remove the entire external drive, or select only specific locations and file types to index, to speed access.

    After a change, you might want to Rebuild the index, which will take some time, but just once.

You can also use Microsoft/Sysinternals Process Explorer for details on what processes are consuming resources. Try the following to get a better view:

  • Run Process Explorer as Administrator.
  • Add columns for Disk Read and Writes, and for I/O read and Writes, to see if those resources are a bottleneck, rather than CPU.
  • Click on a Process to view details, such as the myriad threads running under System. Note that not all threads might be active.

Process Explorer -- Threads

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  • Interesting suggestion, I never rebuilt the index. I added a 2nd internal HDD recently, I wonder if the index just got confused and started looping for whatever reason. Maybe it has nothing to do with it at all, but I will still try this and see what happens.
    – cst_ramirez
    Commented Jan 23 at 23:08
  • The external drive was not indexed, but I rebuilt the index anyway. The problem persists though. You mentioned Windows Defender, but I can see what processes it uses in the task manager (antimalware service executable, etc.), and it is always the 'System' process. I have a feeling this is something else. Any good way to see which thread in the System process in responsible for this?
    – cst_ramirez
    Commented Jan 29 at 16:04
  • @cst_ramirez, I've added info on using Microsoft's own Process Explorer to get a better handle (no pun intended) on what threads under System process might cause the issue.
    – DrMoishe Pippik
    Commented Jan 29 at 18:21
  • thanks for the suggestion to use Process Explorer. I added the info to my original post.
    – cst_ramirez
    Commented Jan 30 at 18:59
  • unfortunately I've rolled back all feature and quality updates to no change, and reinstalled Windows twice, once while keeping files, and once while deleting them. I'm certain it will do nothing. I'm currently trying to teach myself xperf so I can try and diagnose the problem similar to what Florian Storck was able to do.
    – cst_ramirez
    Commented Jan 30 at 22:10

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