100% CPU usage on idle on i5-8400

WildCard999

Titan
Moderator
It's not normal, did you buy the OS on a flash drive? If so it probably is filled with all sorts of malware and such. If you couldn't afford to buy a proper license then you should of downloaded the Windows 10 ISO directly from Microsoft and skipped the part were it asks you for a CD key.
 
100% usage is hardly 'idle'....

DO you have all chipset/gpu drivers installed?

What does task manager show for the process(es) causing all of the cpu uage?

And what do you mean, 'bought my OS from E-Bay'?

From an uninfected computer, download the OS from Microsoft using their Media Creation tool...(you don't want someone else's bootleg/malware creation media that could be full of who knows what spyware, bitcoin mining applications, etc...)