Fans typically respond to temperatures, not usage as such. If the fins under the cooling fan are clogged with dirt/dust, the fan cannot cool the cpu very well at all, so ends up spinning faster, 'going insane', and doesn't matter if it's 10% usage or 100%.
What youll need to do is monitor the temperatures, hwinfo64, real temp, core temp, speccy, aida64 are all pretty reliable, try 2-3 different ones separately during a long period of the same program usage until you are satisfied that the resulting temps are accurate.
Also, if you haven't cleaned your pc, it'd be advisable to do so. They do have fans pulling air in, so will pull dust in too.