normally it's a virus or badly-coded software. It uses 100% CPU power by several reasons, for example, an infinite loop. You should take a screenshot of your "task manager" window with the processes sorted by CPU usage, so we can know know the source of the problem.

This.

When this happened to me on my old computer, it was a malware that was constantly downloading files to my computer.

Exactly, a trojan/downloader can also overload CPU. Funny thing that they usually try to sneak using the name of a real system process XD

Right click taskbar, task manager, processes tab... Look through the list, in the middle division it should tell you how much processor is each process using... Tell us what's the name of the process and we should be able to fix it. :3

Maybe is not the software but the hardware. Maybe your CPU is load to 100% because the CPU is way too hot!
I recommend you to download Coretemp to check your CPU temp but is complicated so I recommend you Speccy

Speccy 1.14.288
http://www.filehippo.com/download_s.....2e5a33a1c43a5/

Once you finish download,take a pic of your temp.
Then show it again on our site or this.
(Or on your page itself)

Send me a note . I have some tips and utilities that you can run for a simple fix.

its just cause ya have way too many unneeded processes running. start the task manager and look through what you are running. turn em off my pressin 'windows key' and 'r' and typing 'msconfig'. go to the services tab and disable services you do not used. BE CAREFUL! some services are needed such as power, time, etc. be very very careful when turnin off services. now go to the startup tab and turn off programs that ya dont want to have start up. keep things like anti virus and 'Microsoft ® windows operating system' enabled. if ya check 'no gui boot' and go to advanced options and use all the ram and processors to start your windows os, that should be fine. it is most likely malware downloadin files or too many processes. so after ya do this, scan for viruses with somethin free like microsoft security essentails cause its also award winning

try that and tell me what happened