CPU usage unstable? HELP!

[MisterCamper]

So a week ago while playing diablo3 I've noticed something is wrong... it was very laggy so I decided to put all settings down to low even tho recommended was ultra settings. Then I went to play other games such as cs:go and lol when I realized that even with ultra or very low settings the fps is under 60 ? This is a trouble since it was always 100+ . I went to reinstall windows with clean installation and formated all drives but that didn't help me. I suspect the faulty is in cpu since on HWMonitor it the cpu usage is unstable and easily reaches 100% on some cores when I'm not even doing any gaming.
My RIG : 8gb kingston DDR3 RAM, i5 4690k, msi z97 gaming3 and msi GTX 960 2GB

 

[techgeek]

Go into your Power settings and set the Power Plan to High Performance. It could be that Windows is lowering you multiplier when it shouldn't be.