Why is my PC using up so much CPU power when I download files?

Nick October 30, 2014
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Whenever i’m downloading something either through internet or from another computer in my network the process “system” uses alot of CPU power, crippling my computer. I have used process explorer to narrow it down to ndis.sys being the culprit. But from what I can find on Google they all say that its related to the network card. However I have tried another PCI network card and also a “USB network adapter”, whilst disabling the other cards and the problem persists.

My spec:
Core i5 3570k
8GB ram
Asus GTX 660

  1. Jan F.
    October 30, 2014 at 8:24 pm

    Click Start and type "cmd" into the search box
    right-click and "Run as administrator" on the cmd.exe result
    In the elevated command prompt type "sfc /scannow"
    * keep your installation CD/DVD at hand as you might need it to repair damaged files

    Make sure your anti-virus is fully updated and run a full system scan.

    "ndis.sys" ought to be a legitimate Windows system file and if it's neither corrupt (sfc checks that) nor infected (anti-virus checks that) the source is somewhere else.

    Once you scanned your computer temporarily disable your anti-virus and download something (safe) again to see if the issue is related to real-time scanning.

  2. ha14
    October 30, 2014 at 7:47 pm

    This application will scan and remove software that may cause problems with Chrome.
    https://www.google.com/chrome/srt/
    https://productforums.google.com/forum/#!topic/chrome/8L9S6EcWYNc

    • Mathew
      October 31, 2014 at 11:23 am

      This thing worked for me.... thanks for the link

    • ha14
      October 31, 2014 at 1:48 pm

      thanks for your feedback, do you know what was causing it?