gytis.jonika :
So everything was going good till today, i decided to check how much dust is in my pc and it was a lot, is that the problem? Do I need to clean dust or something? Im getting huge lag spikes around 20 fps while i was getting 120 fps on league of legends, GTX 980 i5 4460
Get the dust out of it. Pay attention to the HSF(s)/Radiator(s). That buildup insulates the parts meant to rid the heat so they can't get rid of it. That alone can cause your temp readings with little to no load.
Considering, you'll also need to remember to periodically open up the case and dust inside to prevent it from happening again.