Computer lagging REALLY bad!

[icarsis]

I just built my PC about a month ago, worked PERFECT amazing actually really loved it, played games like CS:GO, COD4, Farcry 3 all those perfect, today started my PC up and it's lagging! Browsers are slow, games lag spike INSANELY lag spike.... I really don't know whats wrong I just reformatted my PC and It's still doing it!

PC SPECS:
i5-4690k
GTX 970
8GB Ram
600W PSU
MSI Z87-G41 PC Mate LGA 1150
128 GB SSD
1TB HDD

 

[turkey3_scratch]

Virus? Probably some form of malicious code running. Check task manager and see what's using a lot of resources.