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

Nick October 30, 2014

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.

    • 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?