Royal Demon

Hello i have been having a minour problem lately and it has been stressing me tf out. Pretty much my case fans are at there default settings in the bios, but whenever i do a fan curve the system just doesnt want to listen, when im in the bios the fan curve works how it is suppose to but as soon as i launch into windows my fans are going up and down like crazy from 900rpm to 1400rpm. I know it is a minour issue but i want to do a custom fan curve. Any help will be appreciated